Configure pep8speaks to use 88 character line length

[mkelley]

I'm happy with black formatting, which uses an 88 character line length limit. Astropy has also moved to formatting code with black. Shall we change pep8speaks to use an 88 character limit? (see #394 for an example with 80 character line length but code formatted with black).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.52%. Comparing base (1315915) to head (f59f7a7).
Report is 31 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #395   +/-   ##
=======================================
  Coverage   77.52%   77.52%           
=======================================
  Files          81       81           
  Lines        7096     7096           
=======================================
  Hits         5501     5501           
  Misses       1595     1595           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[hhsieh00]

sounds good