refactor: remove six

[Tieqiong]

closes #92

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.96%. Comparing base (46c5082) to head (8ef84a7).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #114   +/-   ##
=======================================
  Coverage   98.96%   98.96%           
=======================================
  Files           6        6           
  Lines        1261     1261           
=======================================
  Hits         1248     1248           
  Misses         13       13           

Files with missing lines	Coverage Δ
tests/conftest.py	72.72% <100.00%> (ø)

[sbillinge]

Nice!!!!!!