Recursively get submodules before generating the sdist (AcademySoftwareFoundation#1152)

Author: JeanChristopheMorinPerso

.github/workflows/python-package.yml

@@ -124,9 +124,11 @@ jobs:
 
   package_sdist:
     needs: py_build_test
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/[email protected]
+      with:
+        submodules: 'recursive'
 
     - uses: actions/setup-python@v2