upgrade metadata action to v6 in release

Author: atkrad

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
 
       - name: Docker metadata
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: deployah/deployah
           # 'latest' only on stable tags (no pre-release suffix like -alpha, -beta, -rc)