Add coverage reporting with codecov.

.github/workflows/test.yml

@@ -16,19 +16,24 @@ jobs:
             django-version: 4.0
       fail-fast: false
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v3
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v1
+        uses: actions/setup-python@v3
         with:
           python-version: ${{ matrix.python-version }}
+          cache: 'pip'
 
       - name: Install dependencies
         run: |
-          pip install -U pip
+          pip install -U pip coverage
           pip install "Django~=${{ matrix.django-version }}.0" .
 
       - name: Run Tests
         run: |
           echo "$(python --version) / Django $(django-admin --version)"
-          python -m unittest discover
+          coverage run --source=dj_database_url --branch -m unittest discover
+          coverage report
+          coverage xml
+
+      - uses: codecov/codecov-action@v2