add github workflow for test-pypi cross-OS wheel builds

Author: AlePalu

.github/workflows/testpypi-linux.yml

@@ -14,6 +14,7 @@ jobs:
       - uses: actions/checkout@v6
         with:
           persist-credentials: false
+          submodules: recursive
 
       # Used to host cibuildwheel
       - uses: actions/setup-python@v6

.github/workflows/testpypi-macos.yml

@@ -14,6 +14,7 @@ jobs:
       - uses: actions/checkout@v6
         with:
           persist-credentials: false
+          submodules: recursive
 
       # Used to host cibuildwheel
       - uses: actions/setup-python@v6