Change logic in taxcalc/validation/taxsim/ so it works with new TAXSIM-27

[martinholmer]

This pull request revises the old validation logic, which worked with TAXSIM 9, so that it now works with Internet TAXSIM version 27.

Note that the minimum required version of pandas has been increased from 0.22 to 0.23 because the new validation test logic relies on this new argument-order-preservation feature when the DataFrame constructor is passed a dictionary as data:

[codecov-io]

Codecov Report

Merging #2140 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2140      +/-   ##
==========================================
- Coverage   99.91%   99.91%   -0.01%     
==========================================
  Files          16       16              
  Lines        3520     3519       -1     
==========================================
- Hits         3517     3516       -1     
  Misses          3        3

Impacted Files	Coverage Δ
taxcalc/decorators.py	100% <0%> (ø)	⬆️

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