Replace leftover 'windows-latest' in wheel build

See e7c8827

.github/workflows/build_upload_pypi_wheels.yml

@@ -12,7 +12,7 @@ jobs:
         architecture: [x64]
         python-version: [3.6, 3.7, 3.8]
         include:
-          - os: windows-latest
+          - os: windows-2019
             wheelname: win
           - os: macos-latest
             wheelname: macos
@@ -63,7 +63,7 @@ jobs:
           pip-wheel-args: '--no-deps -w wheelhouse'
 
       - name: Create source distribution
-        if: matrix.os == 'windows-latest' && matrix.python-version == '3.8'
+        if: matrix.os == 'windows-2019' && matrix.python-version == '3.8'
         run: |
           python setup.py sdist
         shell: bash
@@ -74,7 +74,7 @@ jobs:
             name: wheels
             path: wheelhouse/*-${{ matrix.wheelname }}*.whl
       - name: Upload source dist to PyPI
-        if: matrix.os == 'windows-latest' && matrix.python-version == '3.8'
+        if: matrix.os == 'windows-2019' && matrix.python-version == '3.8'
         env:
           TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
           TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}