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-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -14,6 +14,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Build
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           push: false

.github/workflows/publish.yml

@@ -38,7 +38,7 @@ jobs:
 
       - name: Build and push Docker image
         id: push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           push: true