Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/docs-lint.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: github/super-linter/slim@v5.0.0
         env:

.github/workflows/docs.yml

@@ -13,7 +13,7 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - uses: ./.github/workflows/build-jekyll-site-action
               with:

.github/workflows/tests.yml

@@ -10,7 +10,7 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - uses: shivammathur/setup-php@v2
               with:
@@ -44,7 +44,7 @@ jobs:
                       composer-flags: '--ignore-platform-reqs'
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
               with:
                 fetch-depth: 0
 
@@ -74,7 +74,7 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - uses: shivammathur/setup-php@v2
               with:
@@ -92,7 +92,7 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - uses: shivammathur/setup-php@v2
               with: