Update .github/workflows/tests.yml

Author: curquiza

.github/workflows/tests.yml

@@ -53,4 +53,6 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - name: Build
-      run: cargo check --example web_app --target wasm32-unknown-unknown
+      run:  |
+        rustup target add wasm32-unknown-unknown
+        cargo check --example web_app --target wasm32-unknown-unknown