pipenv attempt for github workflow actions

Author: Kenneth Reitz

.github/workflows/ci.yml

@@ -25,9 +25,8 @@ jobs:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
-        python -m pip install --upgrade pip
-        pip install flake8 pytest
-        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+        python -m pip install --upgrade pip pipenv
+        pipenv install --dev
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names