[BUG] For Discussion - Fixes risky risk free rate

[humdings]

Our default risk-free-rate is the 10-year yield, which is
considered risky by 99% of investors.

This is a quick fix to make the default the 3-month T-bill rate,
which is a widely used risk-free instrument.

An api function to set the risk free rate within initialize might be a
worthwhile project, but just changing this one string solves the
bulk of the issue.

[humdings]

I would be curious to hear others input on what sorts of unexpected consequences might show up as a result of swapping out the 10-year yield for the 3-month T-bill as the default risk-free-rate.

The tests that failed are risk metric calculations, which should be expected because the expected outcome used in the test cases are wrong.

I can fix the test cases if we feel changing this default behavior is worth it.

[freddiev4]

Going to close this b/c it's 3 years old and not sure where we want this to go.