minor #949 Upgrade actions/checkout from v5 to v6 (OskarStark)

This PR was merged into the main branch.

Discussion
----------

 Upgrade actions/checkout from v5 to v6

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| Docs?         | no
| Issues        | --
| License       | MIT

Commits
-------

244ce6e Upgrade actions/checkout from v5 to v6

Author: OskarStark

.github/workflows/code-quality.yaml

@@ -24,7 +24,7 @@ jobs:
                 php-version: [ '8.4' ]
         steps:
             - name: Checkout
-              uses: actions/checkout@v5
+              uses: actions/checkout@v6
 
             - name: Configure environment
               run: |

.github/workflows/doctor-rst.yaml

@@ -18,7 +18,7 @@ jobs:
         runs-on: ubuntu-latest
         steps:
             - name: Checkout
-              uses: actions/checkout@v5
+              uses: actions/checkout@v6
 
             - name: Create cache dir
               run: mkdir .cache

.github/workflows/integration-tests.yaml

@@ -38,7 +38,7 @@ jobs:
             SYMFONY_REQUIRE: ${{ matrix.symfony-version || '>=7.3' }}
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - name: Up the examples services
               working-directory: examples
@@ -83,7 +83,7 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - name: Setup PHP
               uses: shivammathur/setup-php@v2

.github/workflows/unit-tests.yaml

@@ -41,7 +41,7 @@ jobs:
             SYMFONY_REQUIRE: ${{ matrix.symfony-version || '>=7.3' }}
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - name: Configure environment
               run: |