Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/ci.yaml

@@ -6,7 +6,7 @@ jobs:
   pre-commit:
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: snok/install-poetry@v1
         with:
           virtualenvs-create: true
@@ -24,7 +24,7 @@ jobs:
   fast-tests:
     runs-on: ubuntu-20.04
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Unit tests
         run: bazel test //src/... //test/aspect:all
       - name: Execute Mypy
@@ -34,7 +34,7 @@ jobs:
     runs-on: ubuntu-20.04
     needs: [ pre-commit, fast-tests ]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Integration tests - Aspect
         run: ./test/aspect/execute_tests.py
 
@@ -46,7 +46,7 @@ jobs:
           mkdir --parents /tmp/bin
           wget --no-verbose https://github.com/bazelbuild/buildtools/releases/download/v6.1.2/buildozer-linux-amd64 -O /tmp/bin/buildozer
           chmod +x /tmp/bin/buildozer
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Integration tests - Applying fixes
         run: |
           export PATH=/tmp/bin:$PATH
@@ -55,7 +55,7 @@ jobs:
   # tests:
   #   runs-on: ubuntu-20.04
   #   steps:
-  #   - uses: actions/checkout@v3
+  #   - uses: actions/checkout@v4
   #   - uses: snok/install-poetry@v1
   #     with:
   #       virtualenvs-create: true