bump pycodestyle

[asherf]

Problem

flake8 Plugins (flake8-django, flake8-buitlins) refuse to load into pants.
Seeing this;

Exception message: Could not satisfy all requirements for pycodestyle==2.4.0:
    pycodestyle==2.4.0(from: pantsbuild.pants.contrib.python.checks==1.25.0.dev0->pantsbuild.pants.contrib.python.checks.checker==1.25.0.dev0), pycodestyle<2.6.0,>=2.5.0(from: flake8-builtins==1.4.2->flake8)

Solution

Trying to bump pycodestyle.
See if #7158 / #6450 are somehow fixed.

Result

work with flake8 plugins