Use proper line break character for PowerShell

Author: molinav

.github/workflows/basemap-for-windows.yml

@@ -190,7 +190,7 @@ jobs:
           TWINE_PASSWORD: "${{ secrets.PYPI_TOKEN }}"
           TWINE_REPOSITORY_URL: "${{ secrets.PYPI_REPOSITORY_URL }}"
         run: |
-          python -m twine check                                               \
+          python -m twine check                                               `
               ${{ env.PKGDIR }}/dist/*-win*.whl
-          python -m twine upload --skip-existing                              \
+          python -m twine upload --skip-existing                              `
               ${{ env.PKGDIR }}/dist/*-win*.whl