Merge pull request #221 from jyooru/ci/python310

ci: test python 3.10

Author: bee-san

.github/workflows/main.yaml

@@ -6,7 +6,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.6', '3.7', '3.8', '3.9']
+        python-version: ['3.6', '3.7', '3.8', '3.9', '3.10']
         os: [ubuntu-latest, windows-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     name: Python ${{ matrix.python-version }} on ${{ matrix.os }}