Incorrect 2021 *_brk5 and *_brk6 policy parameter values

[martinholmer]

The II and PT _brk5 and _brk6 amounts of all the filing unit types are incorrect. It appears as if the 2021 values were incorrectly specified to be the same as the 2022 values. You can check IRS (or any other reliable source) for the correct 2021 values.

Being human, we all makes mistakes, especially when doing tedious tasks. Humans making mistakes is to be expected, which is why source code should be tested. The maintainers of Tax-Calculator need to ask themselves why their testing strategy is failing to find such mistakes.

@MattHJensen @jdebacker @donboyd5

[MaxGhenis]

It looks like the 2022 values are correct, and 2021 are incorrect. If it's helpful, @nikhilwoodruff added these to openfisca-us in https://github.com/PolicyEngine/openfisca-us/blob/master/openfisca_us/parameters/irs/income/bracket.yaml

[jdebacker]

Resolved with PR #2652.