More shots in the dark

.github/workflows/rust.yml

@@ -18,6 +18,8 @@ jobs:
     - uses: actions/checkout@v2
     - name: Add WASM target
       run: rustup target add wasm32-wasi
+    - name: Install wasm-opt (binaryen)
+      run: apt install binaryen
     - name: Build
       run: ./build-all.sh --verbose
     - name: Run tests