Fix Windows CI: Use python -m pytest instead of pytest command (#811)

* Initial plan

* Fix Windows CI pytest command to use python -m pytest

Co-authored-by: Routhleck <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: Routhleck <[email protected]>

Author: Copilot

.github/workflows/CI-models.yml

@@ -81,4 +81,4 @@ jobs:
           pip install -e .
       - name: Test with pytest
         run: |
-          pytest tests/
+          python -m pytest tests/

.github/workflows/CI.yml

@@ -112,4 +112,4 @@ jobs:
         env:
           MPLBACKEND: Agg  # Use non-interactive backend for matplotlib
         run: |
-          pytest brainpy/
+          python -m pytest brainpy/