Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...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/linters.yml

@@ -23,7 +23,7 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Setup PHP"
         uses: shivammathur/setup-php@v2
@@ -49,7 +49,7 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Setup PHP"
         uses: shivammathur/setup-php@v2
@@ -75,7 +75,7 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Setup pnpm"
         uses: pnpm/action-setup@v4
@@ -100,7 +100,7 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Setup pnpm"
         uses: pnpm/action-setup@v4
@@ -125,7 +125,7 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Setup PHP"
         uses: shivammathur/setup-php@v2
@@ -151,7 +151,7 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Setup pnpm"
         uses: pnpm/action-setup@v4

.github/workflows/publish.yml

@@ -17,7 +17,7 @@ jobs:
       url: https://extensions.typo3.org/extension/extension_builder/
     steps:
       - name: "Checkout"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Publish new version to TER"
         uses: tomasnorre/typo3-upload-ter@v2

.github/workflows/test-documentation.yml

@@ -20,7 +20,7 @@ jobs:
     timeout-minutes: 15
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Test if the documentation will render without warnings"
         run: |

.github/workflows/tests.yml

@@ -30,7 +30,7 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: "Cache Composer dependencies"
         uses: actions/cache@v4