Fix kBET test for 1.1.6

[mumichae]

• update python versions
• update kbet test margin and add random kbet tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.56%. Comparing base (5547cd1) to head (abc6c6d).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #420      +/-   ##
==========================================
+ Coverage   54.69%   58.56%   +3.86%     
==========================================
  Files          22       22              
  Lines        1682     1682              
==========================================
+ Hits          920      985      +65     
+ Misses        762      697      -65     

Flag	Coverage Δ
unittests	58.56% <ø> (+3.86%)	⬆️

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see 4 files with indirect coverage changes