Pin flake8 in pre-commit
Pin flake8 in pre-commit

By default, pre-commit will install the latest
flake8 in its own virtual environment.
This pins the flake8 version to the same
version in requirements/dev.txt

See https://github.com/pre-commit/pre-commit-hooks/issues/332

The latest flake8 includes breaking changes,
which are too numerous to address right now.
I've made a ticket to upgrade flake8:
https://openscience.atlassian.net/browse/PLAT-1164

adlius/osf.io,brianjgeiger/osf.io,brianjgeiger/osf.io,mattclark/osf.io,baylee-d/osf.io,aaxelb/osf.io,cslzchen/osf.io,felliott/osf.io,saradbowman/osf.io,mfraezz/osf.io,brianjgeiger/osf.io,Johnetordoff/osf.io,HalcyonChimera/osf.io,Johnetordoff/osf.io,HalcyonChimera/osf.io,CenterForOpenScience/osf.io,pattisdr/osf.io,CenterForOpenScience/osf.io,mfraezz/osf.io,baylee-d/osf.io,cslzchen/osf.io,cslzchen/osf.io,pattisdr/osf.io,saradbowman/osf.io,HalcyonChimera/osf.io,HalcyonChimera/osf.io,pattisdr/osf.io,mattclark/osf.io,felliott/osf.io,adlius/osf.io,adlius/osf.io,mattclark/osf.io,CenterForOpenScience/osf.io,adlius/osf.io,CenterForOpenScience/osf.io,aaxelb/osf.io,felliott/osf.io,cslzchen/osf.io,mfraezz/osf.io,Johnetordoff/osf.io,mfraezz/osf.io,brianjgeiger/osf.io,aaxelb/osf.io,felliott/osf.io,baylee-d/osf.io,Johnetordoff/osf.io,aaxelb/osf.io