remove flake8-colors

they break `--format` in incompatible ways:
and3rson/flake8-colors#12

Author: asottile

tox.ini

@@ -25,7 +25,6 @@ basepython = python3
 skip_install = true
 deps =
     wheel
-    flake8-colors
 commands =
     python setup.py -qq bdist_wheel
     pip install --force-reinstall -U --pre --find-links ./dist/ flake8
@@ -39,7 +38,6 @@ skip_install = true
 deps =
     flake8
     flake8-bugbear
-    flake8-colors
     flake8-docstrings>=1.3.1
     flake8-import-order>=0.9
     flake8-typing-imports>=1.1
@@ -163,4 +161,3 @@ exclude =
 max-complexity = 10
 import-order-style = google
 application-import-names = flake8
-format = ${cyan}%(path)s${reset}:${yellow_bold}%(row)d${reset}:${green_bold}%(col)d${reset}: ${red_bold}%(code)s${reset} %(text)s