chore: Checkout submodules in CI

Author: franky47

.github/workflows/cmake.yml

@@ -20,6 +20,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
+      with:
+        submodules: recursive
 
     - name: Configure CMake
       # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.