github: drop Python 3.6 from CI builds
The Windows backend no longer works on Python 3.6. Also the macOS build
on 3.6 had to build PyObjC from source and took a long time.
@@ -13,7 +13,7 @@ jobs:
strategy:
matrix:
os: [ubuntu-latest, windows-latest, macos-latest]
- python-version: [3.6, 3.7, 3.8, 3.9]
+ python-version: [3.7, 3.8, 3.9]
steps:
- uses: actions/checkout@v2
- name: Set up Python ${{ matrix.python-version }}
