Bump docker/build-push-action from 2.5.0 to 6.15.0 (#199)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 2.5.0 to 6.15.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@ad44023...471d1dc)

---
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]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/build-docker.yml

@@ -26,7 +26,7 @@ jobs:
           images: domna/pyelli
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
+        uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4
         with:
           context: .
           push: true