Update rust.yml

Author: gkorland

.github/workflows/rust.yml

@@ -13,6 +13,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
+    - name: git submodule
+      run: |
+        git submodule sync
+        git submodule update --init
     - name: Install dependencies
       run: rustup component add rustfmt --toolchain stable-x86_64-apple-darwin
     - name: Build