Bump actions/checkout from 2 to 2.3.4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 2.3.4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v2.3.4)

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

.github/workflows/ghcr.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.4
 
       - name: Get branch names
         id: branch-name

.github/workflows/rebase.yml

@@ -8,7 +8,7 @@ jobs:
     if: github.event.issue.pull_request != '' && contains(github.event.comment.body, '/rebase')
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           token: ${{ secrets.PAT_TOKEN }}
           fetch-depth: 0 # otherwise, you will failed to push refs to dest repo

.github/workflows/sync-release-version.yml

@@ -8,7 +8,7 @@ jobs:
   update-version:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
         with:
           fetch-depth: 0
       - name: Sync release version.

.github/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
     name: Test github-changelog-generator
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.3.4
       - name: shellcheck
         uses: reviewdog/[email protected]
       - name: Run github-changelog-generator