Add support for Python 3.10 (#102)

Author: hugovk

.github/workflows/main.yml

@@ -19,6 +19,8 @@ jobs:
             tox_env: "py38"
           - v: "3.9"
             tox_env: "py39"
+          - v: "3.10"
+            tox_env: "py310"
           - v: "3.9"
             tox_env: "linting"
         os: [ubuntu-latest, windows-latest]
@@ -27,9 +29,9 @@ jobs:
         run: |
           git config --global core.autocrlf false
           git config --global core.eol lf
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - name: Set up Python
-        uses: actions/setup-python@v1
+        uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python.v }}
       - name: Install tox