Bork v4.0.1

Bork v4.0.1 has been released. Most of the work was behind-the-scenes stuff, like improving CI for Bork itself.

As always, it's available via pip: https://pypi.org/project/bork/4.0.1/

Notable changes you may notice are:

• Dropped support for Python 3.5 because the latest Twine requires 3.6+.
• When Bork runs Twine, it uses --repository instead of --repository-url, which allows you to use ~/.pypirc. (#153, #156)
• Bork is now released as a zipapp!

(Shame about that file size for the zipapp, though. ;~;)