no longer need cython as we have wheels for all packages

.travis.yml

@@ -32,7 +32,6 @@ python:
 # we install here, although we uninstall below
 install:
     - pip install --upgrade pip
-    - pip install cython # this can go once we have scipy wheels for 3.8
     - pip install -r requirements.txt
     - pip install -r test_requirements.txt --upgrade --upgrade-strategy only-if-needed
     - pip install -r docs_requirements.txt