mamba environment file

Author: peter-urban

.github/workflows/test_notebooks.yml

@@ -14,7 +14,7 @@ jobs:
 
     runs-on: ${{matrix.os}}
     steps:
-    - uses: actions/setup-python@v3
+    - uses: actions/setup-python@v5
       with:
         python-version: ${{matrix.python_version}}