revised teaser installation

.github/workflows/python-package.yml

@@ -19,7 +19,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip wheel setuptools
         python -m pip install flake8
-        if [ -f requirements.dev.txt ]; then pip install -r requirements.dev.txt;  else pip install .[testing]; fi
+        if [ -f requirements.dev.txt ]; then pip install -r requirements.dev.txt;  else pip install -e .; fi
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names