need recursive submodules

.github/workflows/wheels.yml

@@ -14,7 +14,7 @@ jobs:
     - uses: actions/checkout@v2
       with:
         fetch-depth: 0  # Optional, use if you use setuptools_scm
-        submodules: true  # Optional, use if you have submodules
+        submodules: recursive  # Optional, use if you have submodules
 
     - name: Build SDist
       run: |