Update docker/build-push-action action to v7 (#66)

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

Author: renovate[bot]

.github/workflows/build-and-push.yaml

@@ -32,7 +32,7 @@ jobs:
           echo "TAG=$tag" >> $GITHUB_OUTPUT
       
       - name: Build image and push to GitHub Container Registry
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@v7
         with:
           tags: |
             ghcr.io/appuio/mastodon-openshift/mastodon:latest