build(deps): 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>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -113,7 +113,7 @@ jobs:
       id: extract_tag
 
     - name: Build and push - New Push
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       if: ${{ startsWith(github.ref, 'refs/tags/v') != true && github.event_name != 'pull_request' }}
       with:
         context: .
@@ -130,7 +130,7 @@ jobs:
         tags: cloudnativelabs/kube-router-git:${{ steps.extract_branch.outputs.branch }}
 
     - name: Build and push - New PR
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       if: github.event_name == 'pull_request'
       with:
         context: .
@@ -144,7 +144,7 @@ jobs:
 
     # Tagging a release candidate, don't update latest
     - name: Build and push - New Tag (Release Candidate)
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       if: ${{ startsWith(github.ref, 'refs/tags/v') && contains(github.ref, '-rc') }}
       with:
         context: .
@@ -163,7 +163,7 @@ jobs:
 
     # Tagging a proper release, update latest
     - name: Build and push - New Tag
-      uses: docker/build-push-action@v5
+      uses: docker/build-push-action@v6
       if: ${{ startsWith(github.ref, 'refs/tags/v') && ! contains(github.ref, '-rc') }}
       with:
         context: .