Run pytest with different Python versions in GitHub actions

.github/workflows/ci.yml

@@ -3,20 +3,25 @@ name: CI
 on: [push, pull_request]
 
 jobs:
-  build:
+  test:
+    name: test w/ Python
     runs-on: ubuntu-latest
-
+    strategy:
+      matrix:
+        python-version: ["3.7", "3.10"]
     steps:
-      - name: Checkout source
-        uses: actions/checkout@v2
-
+      - uses: actions/checkout@v2
       - name: Install dependencies
-        run: |
-          pip install -r requirements-dev.txt
-          pip install flake8
-
-      - name: flake8
-        run: flake8 .
-
+        run: pip install -r requirements-dev.txt
       - name: Run tests
         run: pytest
+
+  flake8-formatting:
+    name: code autoformatting with flake8
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install dependencies
+        run: pip install flake8
+      - name: Check code with flake8
+        run: flake8 .