Add pyup ignore entries for latest pyflakes/pycodestyle (#4098)
Add pyup ignore entries for latest pyflakes/pycodestyle (#4098)

Since we can't update to them until there is a newer release of
flake8 that supports the newer versions.

Closes #3425.
Closes #3565.
edmorley/treeherder,KWierso/treeherder,KWierso/treeherder,KWierso/treeherder,edmorley/treeherder,KWierso/treeherder,edmorley/treeherder,edmorley/treeherder