silently install rustup

Author: EmandM

.yamato/desktop-standalone-tests.yml

@@ -93,7 +93,7 @@ desktop_standalone_test_{{ project.name }}_{{ platform.name }}_{{ backend }}_{{
     - git clone https://github.com/Unity-Technologies/mps-common-multiplayer-backend.git
     - pushd mps-common-multiplayer-backend/runtime
     # Install rust
-    - curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+    - curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
     # Build the echo server
     - cargo build --example ngo_echo_server
     # Run the echo server in the background - this will reuse the artifacts from the build