Update docker/build-push-action action to v6 (#171)

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

Author: renovate[bot]

.github/workflows/build.yml

@@ -9,7 +9,7 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v2
       - name: Build
-        uses: docker/build-push-action@v4
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: ./Dockerfile

.github/workflows/publish-docker-image.yml

@@ -31,7 +31,7 @@ jobs:
             intellectualsites/schematic-web
             ghcr.io/IntellectualSites/schematic-web
       - name: Build and push Docker images
-        uses: docker/build-push-action@v4
+        uses: docker/build-push-action@v6
         with:
           context: .
           push: true