expicitly run this step in Git bash

Author: mshafer-NI

.github/workflows/PR.yml

@@ -60,6 +60,7 @@ jobs:
           . test_venv/bin/activate || call test_venv\Scripts\activate
           pip install .
       - name: Lint our own pakage
+        shell: bash
         run: |
           . test_venv/bin/activate || call test_venv\Scripts\activate
           nps lint .