actually update submodules

.github/workflows/cmake.yml

@@ -16,9 +16,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    
-    - name: Checkout submodules
-      run: git submodule init
+      with:
+        # Whether to checkout submodules: `true` to checkout submodules or `recursive` to
+        # recursively checkout submodules.
+        submodules: 'true'
 
     - name: Create Build Environment
       # Some projects don't allow in-source building, so create a separate build directory