Travis CI: Strict flake8 (#1962)

* Travis CI: Strict flake8

Turn the screws all the way down.

* updating DIRECTORY.md

* Switch from flake8 --select to --ignore

* Quotes

* IGNORE=E123,E203,E265,E266,E302,E401,E402,E712,E731,E741,E743,F811,F841,W291,W293,W503

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

Author: cclauss

.travis.yml

@@ -7,8 +7,8 @@ before_install: pip install --upgrade pip setuptools six
 install: pip install -r requirements.txt
 before_script:
   - black --check . || true
-  - flake8 . --count --select=E101,E5,E722,E9,F4,F63,F7,F82,W191 --max-complexity=25 --max-line-length=127 --show-source --statistics
-  - flake8 . --count --exit-zero --max-line-length=127 --statistics
+  - IGNORE=E123,E203,E265,E266,E302,E401,E402,E712,E731,E741,E743,F811,F841,W291,W293,W503
+  - flake8 . --count --ignore=$IGNORE --max-complexity=25 --max-line-length=127 --show-source --statistics
 script:
   - scripts/validate_filenames.py  # no uppercase, no spaces, in a directory
   - mypy --ignore-missing-imports .