Pull submodules before building the source distribution

Author: aMarcireau

.github/workflows/build_wheels.yml

@@ -27,6 +27,8 @@ jobs:
         runs-on: ubuntu-22.04
         steps:
             - uses: actions/checkout@v3
+              with:
+                  submodules: true
             - name: Build sdist
               run: pipx run build --sdist
             - uses: actions/upload-artifact@v3