update docker/build-push-action@v6 and set BUILD_TIME

.github/workflows/docker.yaml

@@ -25,6 +25,8 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
+      - name: Set BUILD_TIME env
+        run: echo BUILD_TIME=$(date -u +"%Y-%m-%dT%H:%M:%SZ") >> ${GITHUB_ENV}
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3
       - name: Set up Docker Buildx
@@ -49,7 +51,7 @@ jobs:
             type=semver,pattern=release
             type=sha
       - name: Build and push Docker image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           platforms: linux/amd64,linux/arm64