Update actions/checkout to v6

Update all occurrences of actions/checkout from v4 and v5 to the
latest v6 version across the documentation and workflow files.

Author: OskarStark

.github/workflows/ci.yaml

@@ -21,7 +21,7 @@ jobs:
 
         steps:
             -   name: "Checkout"
-                uses: actions/checkout@v4
+                uses: actions/checkout@v6
 
             -   name: "Set-up PHP"
                 uses: shivammathur/setup-php@v2
@@ -56,7 +56,7 @@ jobs:
 
         steps:
             -   name: "Checkout"
-                uses: actions/checkout@v4
+                uses: actions/checkout@v6
 
             -   name: "Create cache dir"
                 run: mkdir .cache
@@ -85,7 +85,7 @@ jobs:
 
         steps:
             -   name: Checkout code
-                uses: actions/checkout@v4
+                uses: actions/checkout@v6
                 with:
                     path: 'docs'
 

setup/bundles.rst

@@ -126,7 +126,7 @@ as a starting point for your own GitHub CI configuration:
             runs-on: ubuntu-latest
             continue-on-error: ${{ matrix.stability == 'dev' }}
             steps:
-                - uses: actions/checkout@v5
+                - uses: actions/checkout@v6
 
                 - name: Setup PHP, with composer and extensions
                   uses: shivammathur/setup-php@v2

testing/end_to_end.rst

@@ -733,7 +733,7 @@ Here is a minimal ``.github/workflows/panther.yaml`` file to run Panther tests:
         runs-on: ubuntu-latest
 
         steps:
-          - uses: actions/checkout@v4
+          - uses: actions/checkout@v6
           - uses: "ramsey/composer-install@v2"
 
           - name: Install dependencies