Add build step to check-pr CI job

Author: TheBestTvarynka

.github/workflows/check-pr.yml

@@ -27,4 +27,10 @@ jobs:
       run: 'cargo clippy --all-targets -- -D warnings'
 
     - name: 'Tests'
-      run: 'cargo test'
+      run: 'cargo test'
+
+    - name: 'Add WASM target'
+      run: 'rustup target add wasm32-unknown-unknown'
+
+    - name: 'Build WASM'
+      run: 'cargo build --target wasm32-unknown-unknown'