Setup Python version matrix for GHA (#95)

.github/workflows/tests.yml

@@ -10,33 +10,21 @@ env:
 jobs:
   test:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python: [3.7, 3.8, 3.9, "3.10"]
     steps:
       - uses: actions/checkout@v3
 
-      - name: Set up Python 3.7
-        uses: actions/setup-python@v3
+      - name: Set up Python
+        uses: actions/setup-python@v4
         with:
-          python-version: '3.7'
-
-      - name: Set up Python 3.8
-        uses: actions/setup-python@v3
-        with:
-          python-version: '3.8'
-
-      - name: Set up Python 3.9
-        uses: actions/setup-python@v3
-        with:
-          python-version: '3.9'
-
-      - name: Set up Python 3.10
-        uses: actions/setup-python@v3
-        with:
-          python-version: '3.10'
+          python-version: ${{ matrix.python }}
 
       - name: setup
         run: |
-          python3.10 -m pip install --upgrade pip
-          python3.10 -m pip install --upgrade tox
+          python -m pip install --upgrade pip
+          python -m pip install --upgrade tox
 
       - name: run tests
-        run: python3.10 -m tox -q
+        run: python -m tox -q