Update KY, MD, and VT parameters, variables, and tests

[rickecon]

• make format and make documentation has been run. (You may also want to run make test.)

This PR:

• Updates and fixes Kentucky, Maryland, and Vermont parameters, variables and tests.

[codecov]

Codecov Report

Attention: Patch coverage is 99.56803% with 4 lines in your changes missing coverage. Please review.

Project coverage is 98.44%. Comparing base (9cfa419) to head (6861667).
Report is 17 commits behind head on main.

Files with missing lines	Patch %	Lines
...emographic/tax_unit/head_is_dependent_elsewhere.py	66.66%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #86      +/-   ##
==========================================
+ Coverage   98.40%   98.44%   +0.04%     
==========================================
  Files        1840     1897      +57     
  Lines       27116    27852     +736     
  Branches      142      140       -2     
==========================================
+ Hits        26684    27420     +736     
- Misses        401      403       +2     
+ Partials       31       29       -2     

Flag	Coverage Δ
unittests	98.44% <99.56%> (+0.04%)	⬆️

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