chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/build-test.yml

@@ -25,7 +25,7 @@ jobs:
       HUGO_VERSION: 0.140.2
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           submodules: recursive
           fetch-depth: 0

.github/workflows/hugo.yml

@@ -47,7 +47,7 @@ jobs:
         run: dart-sass --version
 
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           submodules: recursive
           fetch-depth: 0

.github/workflows/lighthouse.yml

@@ -14,7 +14,7 @@ jobs:
       urls: ${{ steps.get_urls.outputs.urls }}
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Hugo
         uses: peaceiris/actions-hugo@v3
@@ -56,7 +56,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Prepare URLs for Lighthouse
         id: prepare_lighthouse_urls

.github/workflows/optimize-images.yml

@@ -28,7 +28,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Node.js
         uses: actions/setup-node@v4