Install before test

.github/workflows/python-package.yml

@@ -27,8 +27,8 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        python -m pip install flake8 pytest
-        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+        pip install flake8 pytest
+        pip install .
     - name: Test with pytest
       run: |
         pytest --doctest-modules --ignore=scripts --ignore=docs