Update docker/build-push-action digest to 31ca4e5 (#166)

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

.github/workflows/docker-publish.yml

@@ -91,7 +91,7 @@ jobs:
       # https://github.com/docker/build-push-action
       - name: Build and push Docker image
         id: build-and-push
-        uses: docker/build-push-action@b32b51a8eda65d6793cd0494a773d4f6bcef32dc
+        uses: docker/build-push-action@31ca4e5d51253d7e4a2317bfe74699cbe3a398a9
         with:
           context: .
           push: ${{ github.event_name != 'pull_request' && steps.paths-changed.outputs.dockerfile == 'true' }}