Fix bug described in issue #405

[martinholmer]

Fixes #405 by using correct PolicyEngine-US name for PUF variable E09900.

The following test failures will be fixed in a subsequent pull request:

E           ValueError: 
E           WEIGHT VARIABLE ACT-vs-EXP DIFFS:
E           WEIGHT_DIFF:sdev,act,exp,atol,rtol= 1142.5726988805463 1140.202438 0.0 0.0005
E tests/test_weights.py:34: ValueError

E           ValueError: 
E           ACT-vs-EXP TAX EXPENDITURE DIFFERENCES:
E           *** actual
E           --- expect
E           ***************
E           *** 1,3 ****
E           ! YR,KIND,EST= 2023 paytax 1385.3
E           ! YR,KIND,EST= 2023 iitax 2236.4
E           ! YR,KIND,EST= 2023 ctc 128.8
E           --- 1,3 ----
E           ! YR,KIND,EST= 2023 paytax 1386.6
E           ! YR,KIND,EST= 2023 iitax 2238.9
E           ! YR,KIND,EST= 2023 ctc 129.1
E           ***************
E           *** 5,7 ****
E           ! YR,KIND,EST= 2023 social_security_partial_taxability 57.3
E           ! YR,KIND,EST= 2023 niit -43.8
E           ! YR,KIND,EST= 2023 cgqd_tax_preference 175.9
E           --- 5,7 ----
E           ! YR,KIND,EST= 2023 social_security_partial_taxability 57.4
E           ! YR,KIND,EST= 2023 niit -43.9
E           ! YR,KIND,EST= 2023 cgqd_tax_preference 176.0
E tests/test_tax_expenditures.py:53: ValueError