Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/automatic-rebase.yml

@@ -14,7 +14,7 @@ jobs:
       )
     steps:
       - name: Checkout the latest code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           fetch-depth: 0 # otherwise, you will fail to push refs to dest repo

.github/workflows/tests.yml

@@ -42,7 +42,7 @@ jobs:
     name: Test - impresscms:${{ matrix.impresscms_version }}; php:${{ matrix.php_version }}; ${{ matrix.database }}; ${{ matrix.os }}; composer:${{ matrix.composer_version }};
     steps:
       - name: Checkouting project code...
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Testing addon...
         uses: impresscms-dev/[email protected]