fix: remove redundant SDKs to reduce space used on Github Runner

.github/workflows/dockerhub-mcp.yml

@@ -10,11 +10,23 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
+      - name: Check and free disk space before build
+        run: |
+          echo "=== Before cleanup ==="
+          df -h
+          echo "Removing unused preinstalled SDKs to free space..."
+          sudo rm -rf /usr/share/dotnet /usr/local/lib/android /opt/ghc || true
+          docker system prune -af || true
+          echo "=== After cleanup ==="
+          df -h
+
       - name: Checkout repository
         uses: actions/checkout@v4
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
+        with:
+          buildkitd-flags: --root /tmp/buildkit
 
       - name: Log in to Docker Hub
         uses: docker/login-action@v3