Bump docker/build-push-action from 4 to 6

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 4 to 6.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v4...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>

Author: dependabot[bot]

.github/workflows/publish-docker.yml

@@ -59,7 +59,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
       - name: Build docker image
-        uses: docker/build-push-action@v4
+        uses: docker/build-push-action@v6
         with:
           build-args: GITLINT_VERSION=${{ inputs.gitlint_version }}
           tags: jorisroovers/gitlint:${{ steps.set_tag.outputs.docker_image_tag }}
@@ -72,7 +72,7 @@ jobs:
 
       # This won't actually rebuild the docker image, but just push the previously built and cached image
       - name: Push docker image
-        uses: docker/build-push-action@v4
+        uses: docker/build-push-action@v6
         with:
           push: ${{ inputs.push_to_dockerhub }}
           build-args: GITLINT_VERSION=${{ inputs.gitlint_version }}