Disable git submodules to prevent cleanup errors

Author: theoddden

.github/workflows/ci-improved.yml

@@ -87,6 +87,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v4
+      with:
+        submodules: false
 
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v5