move unit tests from nose tests to pytest

.github/workflows/main.yaml

@@ -5,17 +5,20 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [3.6, 3.7, 3.8, 3.9, 3.10]
     steps:
       - name: Check out code
         uses: actions/checkout@v2
-      - name: Set up Python
+      - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v2
         with:
-          python-version: [3.6, 3.7, 3.8, 3.9, 3.10]
+          python-version: ${{ matrix.python-version }}
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install -r requirements.txt  # Assumes you have a requirements.txt
+          pip install -r requirements.txt
           pip install -r requirements_dev.txt
       - name: Run tests
         run: |