Fix release pipeline

.github/workflows/release.yml

@@ -16,14 +16,14 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v2
       with:
-        python-version: 3.7
+        python-version: 3.9
     - name: Install dependencies
       run: |
         pip install -e .
         pip install flake8 pytest pytest-cov twine wheel
     - name: Test with pytest
       run: |
-        pytest --cov=./detl --cov-report xml --cov-report term-missing detl/tests.py
+        pytest --cov=./detl --cov-report xml --cov-report term-missing tests/
     - name: Build package
       run: |
         python setup.py sdist bdist_wheel