Update docker/build-push-action action to v7

Author: dependencyupdates[bot]

.github/workflows/build-containers.yml

@@ -58,7 +58,7 @@ jobs:
         id: date
         run: echo "date=$(date '+%FT%TZ')" >> $GITHUB_OUTPUT
       - name: Build and push image to GitHub container registry
-        uses: docker/build-push-action@v6.19.2
+        uses: docker/build-push-action@v7.0.0
         with:
           context: .
           push: true