Bump docker/build-push-action from 2 to 6 (#112)

Author: dependabot[bot]

.github/workflows/docker-build.yml

@@ -21,7 +21,7 @@ jobs:
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GHCR_PAT }}
       - name: Build Docker Image
-        uses: docker/build-push-action@v2
+        uses: docker/build-push-action@v6
         with:
           push: true
           tags: ghcr.io/${{ github.repository_owner }}/gh-act