Remove termbg dependency

[adamchalmers]

We aren't even using the relevant code. If we need it in the future, we can add it back in.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.22%. Comparing base (ed80dc3) to head (d1479b9).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #977      +/-   ##
==========================================
+ Coverage   71.94%   72.22%   +0.27%     
==========================================
  Files          36       36              
  Lines        6666     6642      -24     
==========================================
+ Hits         4796     4797       +1     
+ Misses       1870     1845      -25     

Flag	Coverage Δ
unittests	72.22% <ø> (+0.27%)	⬆️

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