Revert "Do test with Windows on GitHub Actions"

This reverts commit 51cca58094.

.github/workflows/main.yml

@@ -1,21 +0,0 @@
-name: CI on Windows
-
-on: [push]
-
-jobs:
-  build:
-    runs-on: windows-latest
-    strategy:
-      matrix:
-        architecture: [x86, x64]
-
-    steps:
-    - uses: actions/checkout@v2
-    - name: Set up Python
-      uses: actions/setup-python@v1
-      with:
-        architecture: ${{ matrix.architecture }}
-    - name: Install dependencies
-      run:  pip install -U tox
-    - name: Run Tox
-      run:  tox -e py