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]>

.github/workflows/build.yml

@@ -86,7 +86,7 @@ jobs:
         if: github.ref_type == 'branch' && github.ref_name != 'main'
 
       - name: Build image (with cache)
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: ./Dockerfile
@@ -98,7 +98,7 @@ jobs:
         if: github.ref_type == 'branch' && github.ref_name != 'main'
 
       - name: Build image (full)
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: ./Dockerfile