Update docker/build-push-action digest to 91df6b8

Author: renovate[bot]

.github/workflows/docker-publish.yml

@@ -72,7 +72,7 @@ jobs:
       # https://github.com/docker/build-push-action
       - name: Build and push Docker image
         id: build-and-push
-        uses: docker/build-push-action@b5730d24715e542a67be9991a420842b8b072900
+        uses: docker/build-push-action@91df6b874e498451163feb47610c87c4a218c1ee
         with:
           context: .
           push: ${{ github.event_name != 'pull_request' }}