drone.yml: switch linux build step to new OP container

.drone.yml

@@ -30,14 +30,11 @@ steps:
   #    #Todo: fix all the lint errors and add `-set_exit_status` above to enforce linting
 
   - name: build-linux
-    image: cirrusci/flutter:dev
+    image: openpriv/flutter-desktop:dev
     volumes:
       - name: deps
         path: /root/.pub-cache
     commands:
-      - flutter config --enable-linux-desktop
-      - apt-get update
-      - apt-get install -y --no-install-recommends cmake ninja-build clang build-essential pkg-config libgtk-3-dev liblzma-dev
       - flutter build linux
       - mkdir deploy/linux
       - cp -r build/linux/x64/release/bundle/* deploy/linux