New flake8-bugbear version breaks stylecheck

[ftm]

Version 19.3.0 of flake8-bugbear introduced the new warnings B009 and B010 relating to the use of getattr() and setattr() with a constant, i.e. getattr(Input(), "input_type") (PyCQA/flake8-bugbear#55).

This is causing the CI to fail as that pattern is used 7 times in tests/test_widgets.py (see https://travis-ci.org/wtforms/wtforms/jobs/528390668 from #481 for an example failing build). The lines causing the issue are:

• wtforms/tests/test_widgets.py

  Line 86 in a4df965

  getattr(Input(), "input_type")

• wtforms/tests/test_widgets.py

  Line 119 in a4df965

  setattr(basic_widget_dummy_field, "data", "")

• wtforms/tests/test_widgets.py

  Line 121 in a4df965

  setattr(basic_widget_dummy_field, "data", False)

• wtforms/tests/test_widgets.py

  Lines 135 to 137 in a4df965

  	setattr(basic_widget_dummy_field, "data", "hi<>bye")
  	setattr(basic_widget_dummy_field, "name", "f")
  	setattr(basic_widget_dummy_field, "id", "")

• wtforms/tests/test_widgets.py

  Line 156 in a4df965

  setattr(select_dummy_field, "name", "f")