Run flake8 in Travis tests (#25)

jdevera · sdelquin · commit 904bd3055491 · 2019-10-08T12:32:59.000+01:00
So that pull requests are marked as failed if they do not pass flake8
cleanly.
diff --git a/.travis.yml b/.travis.yml
@@ -8,3 +8,4 @@ install:
     - pipenv install -d
 script:
     - pytest
+    - flake8

-Original file line number
+Diff line change
     - pipenv install -d
 script:
     - pytest
 +    - flake8