Bump macbre/push-to-ghcr from 14 to 15 (#164)

Bumps [macbre/push-to-ghcr](https://github.com/macbre/push-to-ghcr) from 14 to 15.
- [Release notes](https://github.com/macbre/push-to-ghcr/releases)
- [Commits](macbre/push-to-ghcr@v14...v15)

---
updated-dependencies:
- dependency-name: macbre/push-to-ghcr
  dependency-version: '15'
  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/push-to-ghcr.yml

@@ -19,7 +19,7 @@ jobs:
 
       # https://github.com/marketplace/actions/push-to-ghcr
       - name: Build and publish a Docker image for macbre/nginx-http3
-        uses: macbre/push-to-ghcr@v14
+        uses: macbre/push-to-ghcr@v15
         with:
           image_name: macbre/nginx-http3
           github_token: ${{ secrets.GITHUB_TOKEN }}