Use corrected CPS age variables

[martinholmer]

This pull request incorporates in Tax-Calculator a new cps.csv.gz file generated by @andersonfrailey's taxdata pull request 172, which responds to @MaxGhenis' bug report in taxdata issue 164.

The new cps.csv.gz file contains fewer children eligible for the Child Tax Credit because prior CPS data incorrectly included those who were 17 years old. As a result, when using CPS data, the dollar amount of tax credits is somewhat lower than before and the dollar amount of income tax liability is slightly higher than before. For example, under current-law policy, the 2018 non-refundable and refundable credits are down by
$1.9 billion (5.6%) and $1.1 billion (1.4%), respectively. These declines in credits raise the 2018 income tax liability by $3.0 billion, which is an increase of about 0.2% (that is, one-fifth of one percent).

This pull request also includes corrected TANF benefits data in the CPS data files.

[codecov-io]

Codecov Report

Merging #1962 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #1962   +/-   ##
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  Coverage     100%    100%           
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  Files          38      38           
  Lines        3748    3748           
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  Hits         3748    3748

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