chore: GH actions to use a python version matrix (#1079)

Author: vj-codes

.github/workflows/main.yml

@@ -20,12 +20,16 @@ jobs:
   build:
     needs: lint
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python: [3.7, 3.9]
+
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python 3.6
+    - name: Set up Python 3.x
       uses: actions/setup-python@v2
       with:
-        python-version: 3.6
+        python-version:  ${{ matrix.python }}
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip