Cap pycodestyle to < 2.6.0

version 2.6.0 introduced new check that now fail on older code branches.
There's no point in adding style changes to old code, cap pycodestyle
instead.

Related-Prod: PRODX-3456
Change-Id: If2619e9e2fe30f71209eebae96d3a9b64499f781
1 file changed