Update docker/metadata-action action to v6

Author: text-html-renovate[bot]

.github/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
     steps:
       - name: Docker meta
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: |
             texthtml/phpcs