Bump docker/build-push-action from 6.7.0 to 6.8.0

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 6.7.0 to 6.8.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](https://github.com/docker/build-push-action/compare/v6.7.0...v6.8.0)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/build_docker_images.yml

@@ -79,7 +79,7 @@ jobs:
         working-directory: spiffworkflow-frontend
         run: echo "$DOCKER_METADATA_OUTPUT_JSON" | jq '.labels' > version_info.json
       - name: Build and push Frontend Docker image
-        uses: docker/build-push-action@v6.7.0
+        uses: docker/build-push-action@v6.8.0
         with:
           # this action doesn't seem to respect working-directory so set context
           context: spiffworkflow-frontend
@@ -135,7 +135,7 @@ jobs:
         working-directory: spiffworkflow-backend
         run: echo "$DOCKER_METADATA_OUTPUT_JSON" | jq '.labels' > version_info.json
       - name: Build and push Backend Docker image
-        uses: docker/build-push-action@v6.7.0
+        uses: docker/build-push-action@v6.8.0
         with:
           # this action doesn't seem to respect working-directory so set context
           context: spiffworkflow-backend
@@ -189,7 +189,7 @@ jobs:
             type=ref,event=tag,enable=true,format=latest
 
       - name: Build and push the connector proxy
-        uses: docker/build-push-action@v6.7.0
+        uses: docker/build-push-action@v6.8.0
         with:
           # this action doesn't seem to respect working-directory so set context
           context: connector-proxy-demo