feat: automatically set the complete date for porter task checkboxes

[stdavis]

I think that this will make updating porter issues slightly nicer. Let me know what you think.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.45%. Comparing base (d397057) to head (db67415).
⚠️ Report is 68 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #475   +/-   ##
=======================================
  Coverage   90.45%   90.45%           
=======================================
  Files           2        2           
  Lines         419      419           
  Branches       77       65   -12     
=======================================
  Hits          379      379           
  Misses         33       33           
  Partials        7        7           

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[jacobdadams]

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