remove windaube from CI

Author: guilyx

.github/workflows/tests.yml

@@ -44,13 +44,11 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: [3.6, 3.7, 3.8, pypy-3.6]
+        os: [ubuntu-latest, macos-latest]
+        python-version: [3.6, 3.7, 3.8]
         exclude:
           - os: macos-latest
             python-version: 3.8
-          - os: windows-latest
-            python-version: 3.6
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python 3.7