Run mypy and flake8 in CI

.travis.yml

@@ -9,6 +9,13 @@ matrix:
   allow_failures:
     - python: nightly
   include:
+    - python: 3.8
+      install:
+        - 'pip install .[qa]'
+      script:
+        # Ignore F401, which are unused imports. flake8 is a primitive tool and is sometimes wrong.
+        - 'flake8 --extend-ignore F401 parso test/*.py setup.py scripts/'
+        - mypy parso
     - python: 3.8.2
       script:
         - 'pip install coverage'