Add Python 3.11 to CI, tox, and trove classifiers

[codecov[bot]]

Codecov Report

Merging #241 (e227da2) into master (d4d00d2) will decrease coverage by 0.95%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #241      +/-   ##
==========================================
- Coverage   80.79%   79.83%   -0.96%     
==========================================
  Files          12        9       -3     
  Lines         781      744      -37     
  Branches      238      220      -18     
==========================================
- Hits          631      594      -37     
  Misses        120      120              
  Partials       30       30              

Impacted Files	Coverage Δ
recurrence/models.py
recurrence/settings.py
recurrence/__init__.py

:mega: We’re building smart automated test selection to slash your CI/CD build times. Learn more