Modernize CI script

* Use built-in cache of setup-python action.
* Run CI against Python 3.10 stable.

Author: srittau

.github/workflows/test-and-lint.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10.0-beta.4"]
+        python-version: ["3.7", "3.8", "3.9", "3.10"]
       fail-fast: false
 
     steps:
@@ -17,11 +17,7 @@ jobs:
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python-version }}
-    - name: Cache dependencies
-      uses: actions/cache@v1
-      with:
-        path: ~/.cache/pip
-        key: ${{ runner.os }}-pip-${{ matrix.python-version }}-${{ hashFiles('requirements.txt') }}
+        cache: pip
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip