Remove support for phaseKey option in harmonic constituents.

[bkeepers]

After #183 and openwatersio/tide-database#33, this removes the phaseKey option because phases are now always relative to UTC.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (ac374a9) to head (15ab4da).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #184   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           11        11           
  Lines          522       522           
  Branches        58        58           
=========================================
  Hits           522       522           

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