chore(deps): update actions/checkout action to v6 (#1200)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/build-docs.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Node
         uses: actions/setup-node@v6

.github/workflows/build-themes.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           ref: ${{ github.ref }}
 

.github/workflows/compress-images.yml

@@ -9,7 +9,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Optimize with Calibre's image actions
         uses: docker://calibreapp/github-image-actions@sha256:23bdfdb399f490dacc86c88cc79c391d76e7ffc1781db586cb28b36b7ca98fb7

.github/workflows/publish.yml

@@ -12,7 +12,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Node
         uses: actions/setup-node@v6