ci: fix windows test command

Author: nattb8

.github/workflows/ui-tests.yml

@@ -86,7 +86,7 @@ jobs:
             test_script: pytest -xs test/test_mac.py::MacTest
           - targetPlatform: StandaloneWindows64
             runs-on: [self-hosted, windows]
-            test_script: pytest -xs test/test_windows.py::WindowsTest
+            test_script: python -m pytest -xs test/test_windows.py::WindowsTest
           # - targetPlatform: Android
           #   runs-on: [ self-hosted, macOS ]
           #   test_script: browserstack-sdk pytest -s ./test/test_android.py --browserstack.config "browserstack.android.yml"