fix: remove non-taxable earning components on tax exemption

[Sudharsanan11]

Issue:
Non-taxable earning components are included in the exemption amount in the income tax computation.

Before:

After:

Backport needed for versions 14 & 15

[nabinhait]

I did not understand the problem statement clearly. As "Meal Allowance" is non-taxable but included in CTC, it should be deducted as an exemption to calculate "Total Taxable Income" correctly.
Please correct me if I am wrong.

[Sudharsanan11]

Yes, it needs to be reduced from the CTC, But including the non-taxable earnings into the Tax Exemption projects the wrong exemption amount.

For example, In the old regime, when the user didn't declare any tax exemptions, he could avail of only the standard deduction of 50,000. But when he has the non-taxable earning of 25,000, the total exemption was showing as 75,000 (standard deductions + non-taxable earnings), which is projecting wrongly.

I'm pushing one more commit to add non-taxable earnings as a separate column for better visibility.