Bump docker/build-push-action from 6.13.0 to 6.15.0 (#292)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 6.13.0 to 6.15.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](https://github.com/docker/build-push-action/compare/ca877d9245402d1537745e0e356eab47c3520991...471d1dc4e07e5cdedd4c2171150001c434f0b7a4)

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

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