Bump docker/build-push-action from 5 to 6

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 5 to 6.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v5...v6)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/quay-publish.yml

@@ -38,7 +38,7 @@ jobs:
           username: ${{ secrets.REGISTRY_USERNAME }}
           password: ${{ secrets.REGISTRY_PASSWORD }}
       - name: Build and publish cwltool_module image to Quay
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: cwltool.Dockerfile
@@ -49,7 +49,7 @@ jobs:
           cache-from: type=gha
           cache-to: type=gha,mode=max
       - name: Build and publish cwltool image to Quay
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: cwltool.Dockerfile