pre-commit-python hook uses pycodestyle from python2

The commit hooks uses the pycodestyle executable but claims to uses the 3 version on Fedora which is named pycodestyle-3. See https://gitlab.freedesktop.org/gstreamer/gst-devtools/blob/master/hooks/pre-commit-python.hook#L22 (Btw we should probably advertise to use dnf instead).

The suggested package is not consistant as pycodestyle on Debian is the version 2, 3 is python3-pycodestyle.

I suppose we want to use the 3 version but I don't know if the naming of packages and the executable is the same with other distros.