Release zfec 1.5.4 - Githubissues

Uploading wheel packages to the Python Package Index would be useful.

This checklist should help:

[x] Prepare wheel and sdist packages: done in #20.
[x] Upload packages to test.pypi.org: done.
[x] Test against Tahoe-LAFS CI: done in tahoe-lafs/tahoe-lafs/pull/804.
[x] Add Python 3.8 to list of languages: done in #25.
[x] Other minor tweaks: #18, #23, #24.
[x] Update NEWS and Changelog: in #29.
[x] Tag zfec-1.5.4, and wait for cibuildwheel to do its thing.
[x] Upload zfec-1.5.4 wheel and sdist packages to PyPI.
[x] Freak out, and wait for someone to yell about something or the other breaking.

tahoe-lafs / zfec