Extend budget period from through 2034 to through 2074

[martinholmer]

This thru74 branch can be merged into the master branch to create a version of Tax-Calculator that has a budget period that extends through 2074 (instead of through 2034).
This branch has not been merged because adding forty extra years to the budget period slows down Tax-Calculator significantly even when analyzing reforms during the standard ten-year budget period.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.42%. Comparing base (404ac22) to head (673ef6f).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2755   +/-   ##
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  Coverage   99.42%   99.42%           
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  Files          13       13           
  Lines        2619     2619           
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  Hits         2604     2604           
  Misses         15       15           

Flag	Coverage Δ
unittests	99.42% <100.00%> (ø)

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Files with missing lines	Coverage Δ
taxcalc/policy.py	100.00% <100.00%> (ø)

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[jdebacker]

@martinholmer Does this extrapolation only work with the TMD file? i.e., the PUF weights only going through 2034 mean that one cannot extrapolate the PUF file from TaxData to the years 2035+

BTW, I'm working on a PR to this branch that uses an update to ParamTools to allow the user to specify the budget window end year so only only needs to extrapolate parameters over the years they wish to use.

[martinholmer]

On the thru74 branch in Tax-Calculator PR #2755, @jdebacker asked:

Does this extrapolation only work with the TMD file? i.e., the PUF weights only going through 2034 mean that one cannot extrapolate the PUF file from TaxData to the years 2035+

The thru74 branch would work with the PUF dataset generated in the taxdata repo if the PUF weights extended through 2074 and the PUF grow factors extended thru 2074.