[TASK] 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] <support@github.com>

Author: dependabot[bot]

.github/workflows/ter-release.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: "Checkout"
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: "Publish new version to TER"
         uses: tomasnorre/typo3-upload-ter@v2

.github/workflows/tests.yml

@@ -14,7 +14,7 @@ jobs:
         php: [ '8.2', '8.3', '8.4' ]
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up PHP Version
         uses: shivammathur/setup-php@v2