Added ks income tax rates

[patneyland]

Added two yaml files for ks tax rates.

[rickecon]

@patrickneyland. This is great. Here are some things you need to update with this PR.

• It looks like the fiscalsim_us/parameters/gov/states/ks/tax/income/credits/taxpayer_credit/rate.yaml file and the fiscalsim_us/parameters/gov/states/ks/tax/income/rate.yaml file are not supposed to be there. You should remove those.
• I am worried about the threshold and rate structure in the two files fiscalsim_us/parameters/gov/states/ks/tax/income/rates/joint.yaml and fiscalsim_us/parameters/gov/states/ks/tax/income/rates/non_joint.yaml. Can that be right?

[rickecon]

@patrickneyland. Update your branch by doing the following steps.

• Go to your main branch in your terminal: git checkout main
• Fetch the new changes from my PR: git fetch upstream
• Merge those changes into your main branch: get merge upstream/main
• Push those changes up to your remote fork main branch: git push origin main
• Switch branches to your ks branch: git checkout ks
• Merge the updates from your main branch into your ks branch: git merge origin/main
• You may have to fix some merge conflicts, but I don't think these will come up.
• Push your changes up to your remote ks branch: git push origin ks
  • This will automatically update your PR, and the message saying, "This branch has conflicts that must be resolved", will go away.