x11/polybar: Update to 3.7.1

[jbo]

Summary

Changelog: https://github.com/polybar/polybar/releases/tag/3.7.1

[tcberner]

This looks like something that you can commit with implicit approval -- if you only need to change distversion/distinfo I trust your instincts to do the right thing :)

You can use something like
Approved by: mentors (implicit)
or what style in the git-log of similar commits you find most comfortable :)