Add a --locked job to CI (#1692)

The current lock file is updated when built, and this fixes the
possibility of that happening again.

Author: alexcrichton

.github/workflows/main.yml

@@ -197,7 +197,7 @@ jobs:
     - name: Install Rust
       run: rustup update stable --no-self-update && rustup default stable
     - run: rustup target add wasm32-wasip1
-    - run: cargo test
+    - run: cargo test --locked
     - run: cargo test -p wit-bindgen-core
     - run: cargo test -p wit-bindgen
     - run: cargo test -p wit-bindgen --all-features