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] <support@github.com>

.github/workflows/ci.yml

@@ -89,7 +89,7 @@ jobs:
       uses: docker/setup-buildx-action@v3
 
     - name: Build only (on commits)
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       if: ${{ github.ref_type != 'tag' }}
       with:
         push: false
@@ -103,7 +103,7 @@ jobs:
         password: ${{ secrets.DOCKERHUB_PASSWORD }}
 
     - name: Build and push (on tag)
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       if: ${{ github.ref_type == 'tag' }}
       with:
         push: true