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/create-pr-updating-extension-test.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - run: |
           echo 'CREATE_PR_BASE='$(echo "${{ github.ref_name }}" | cut -d'-' -f1 ) >> $GITHUB_ENV

.github/workflows/extension-test.yml

@@ -42,7 +42,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       # /home/runner/cache/                               Cache
       # /home/runner/src/                                 Mediawiki installation

.github/workflows/release-and-submit.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-18.04
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2