Update Georgia tax logic

[mitchellpound]

Thanks for contributing! Please remove any top-level sections that do not apply to your changes.

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

What's changed

Updates Georgia tax logic with the following:

• Added Net Operating Loss subtraction from income
• Added ga_other_additions for catchall for unimplemented/ undefined additions (or future additions before they are implemented)
• Added ga_other_subtractions
• Added nonrefundable credit logic - most of Georgia's current credits are non-refundable
• Added nonrefundable credit variables - including ga_other_nonrefundable_credits as catchall for unimplemented credits
• Added tests for nonrefundable credits logic

[codecov[bot]]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (6de2829) 98.45% compared to head (f145513) 98.43%.

Files	Patch %	Lines
...v/states/ga/tax/income/deductions/ga_deductions.py	33.33%	4 Missing :warning:
...ga/tax/income/deductions/ga_itemized_deductions.py	75.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #73 +/- ## ========================================== - Coverage 98.45% 98.43% -0.02% ========================================== Files 1802 1814 +12 Lines 26697 26831 +134 Branches 142 142 ========================================== + Hits 26285 26412 +127 - Misses 381 388 +7 Partials 31 31 ``` | [Flag](https://app.codecov.io/gh/TheCGO/fiscalsim-us/pull/73/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=TheCGO) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/TheCGO/fiscalsim-us/pull/73/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=TheCGO) | `98.43% <95.00%> (-0.02%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=TheCGO#carryforward-flags-in-the-pull-request-comment) to find out more.

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