[Feature] Add TIPS Yields (to maturity)

[deeleeramone]

1. Why?:

   • Expand the fixed income data with more daily benchmark items.
   • TIPS (Treasury Inflation Protected Securities) provide investors with a gauge for an inflation-adjusted, risk-free, rate of return.

2. What?:

   • Adds a new endpoint and data from FRED.
     • obb.fixedincome.government.tips_yields()
     • Historical data represents the current issue ("name") from inception.

3. Impact:

   • More data to maintain.

4. Testing Done:

   • Unit/integration tests.
   • CLI
   • Various start/end date & maturity combinations.