Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/release.yaml

@@ -13,7 +13,7 @@ jobs:
       contents: write
     steps:
       - name: "Checkout"
-        uses: "actions/checkout@v5"
+        uses: "actions/checkout@v6"
       - name: "Verify the release version"
         uses: technote-space/package-version-check-action@v1
         with:

.github/workflows/validate.yaml

@@ -11,7 +11,7 @@ jobs:
     name: "With hassfest"
     runs-on: "ubuntu-latest"
     steps:
-      - uses: "actions/checkout@v5"
+      - uses: "actions/checkout@v6"
       - uses: home-assistant/actions/hassfest@master
 
   hacs: