Fix #5601: Version upgrade for actions/cache (#5603)

<!-- READ ME FIRST: Please fill in the explanation section below and
check off every point from the Essential Checklist! -->
## Explanation
Fix #5601 

This PR updates the workflow to upgrade from `actions/cache@v2`, which
has been deprecated, to `actions/cache@v4`.

## Essential Checklist
<!-- Please tick the relevant boxes by putting an "x" in them. -->
- [x] The PR title and explanation each start with "Fix #bugnum: " (If
this PR fixes part of an issue, prefix the title with "Fix part of
#bugnum: ...".)
- [x] Any changes to
[scripts/assets](https://github.com/oppia/oppia-android/tree/develop/scripts/assets)
files have their rationale included in the PR explanation.
- [x] The PR follows the [style
guide](https://github.com/oppia/oppia-android/wiki/Coding-style-guide).
- [x] The PR does not contain any unnecessary code changes from Android
Studio
([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#undo-unnecessary-changes)).
- [x] The PR is made from a branch that's **not** called "develop" and
is up-to-date with "develop".
- [x] The PR is **assigned** to the appropriate reviewers
([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#clarification-regarding-assignees-and-reviewers-section)).

---------

Co-authored-by: Adhiambo Peres <[email protected]>

.github/workflows/build_tests.yml

@@ -48,7 +48,7 @@ jobs:
       # with Bazel since Bazel can share the most recent cache from an unrelated build and still
       # benefit from incremental build performance (assuming that actions/cache aggressively removes
       # older caches due to the 5GB cache limit size & Bazel's large cache size).
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -191,7 +191,7 @@ jobs:
       # with Bazel since Bazel can share the most recent cache from an unrelated build and still
       # benefit from incremental build performance (assuming that actions/cache aggressively removes
       # older caches due to the 5GB cache limit size & Bazel's large cache size).
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -325,7 +325,7 @@ jobs:
       # with Bazel since Bazel can share the most recent cache from an unrelated build and still
       # benefit from incremental build performance (assuming that actions/cache aggressively removes
       # older caches due to the 5GB cache limit size & Bazel's large cache size).
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -459,7 +459,7 @@ jobs:
       # with Bazel since Bazel can share the most recent cache from an unrelated build and still
       # benefit from incremental build performance (assuming that actions/cache aggressively removes
       # older caches due to the 5GB cache limit size & Bazel's large cache size).
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -580,7 +580,7 @@ jobs:
       # with Bazel since Bazel can share the most recent cache from an unrelated build and still
       # benefit from incremental build performance (assuming that actions/cache aggressively removes
       # older caches due to the 5GB cache limit size & Bazel's large cache size).
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}

.github/workflows/code_coverage.yml

@@ -45,7 +45,7 @@ jobs:
         with:
           version: 6.5.0
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: scripts_cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -130,7 +130,7 @@ jobs:
         with:
           version: 6.5.0
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: scripts_cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -178,7 +178,7 @@ jobs:
       # with Bazel since Bazel can share the most recent cache from an unrelated build and still
       # benefit from incremental build performance (assuming that actions/cache aggressively removes
       # older caches due to the 5GB cache limit size & Bazel's large cache size).
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: test_cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -285,7 +285,7 @@ jobs:
         with:
           version: 6.5.0
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: scripts_cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}

.github/workflows/main.yml

@@ -28,7 +28,7 @@ jobs:
         os: [ubuntu-20.04]
     steps:
       - uses: actions/checkout@v2
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: cache
         with:
           path: ~/.gradle
@@ -119,7 +119,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         with:
           path: ~/.gradle/caches
           key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*') }}-jars-{{ checksum "build.gradle" }}

.github/workflows/static_checks.yml

@@ -115,7 +115,7 @@ jobs:
         with:
           version: 6.5.0
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: scripts_cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}

.github/workflows/stats.yml

@@ -126,7 +126,7 @@ jobs:
       # with Bazel since Bazel can share the most recent cache from an unrelated build and still
       # benefit from incremental build performance (assuming that actions/cache aggressively removes
       # older caches due to the 5GB cache limit size & Bazel's large cache size).
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         if: ${{ steps.track_commits.outputs.new_commits == 'true' }}
         id: cache
         with:

.github/workflows/unit_tests.yml

@@ -35,7 +35,7 @@ jobs:
         with:
           version: 6.5.0
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: scripts_cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -121,7 +121,7 @@ jobs:
         with:
           version: 6.5.0
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: scripts_cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}
@@ -163,7 +163,7 @@ jobs:
       # with Bazel since Bazel can share the most recent cache from an unrelated build and still
       # benefit from incremental build performance (assuming that actions/cache aggressively removes
       # older caches due to the 5GB cache limit size & Bazel's large cache size).
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         id: test_cache
         with:
           path: ${{ env.CACHE_DIRECTORY }}

.github/workflows/wiki.yml

@@ -1,4 +1,5 @@
 name: Deploy to Wiki
+
 on:
   pull_request:
     paths: