Econforge interpolation tests are failing

[mnwhite]

Without making any changes to our code, Econforge interpolation is now failing; see #1457 for what's going on.

Assigning Alan because I have no idea how Econforge works or what it's being used for in HARK.

[mnwhite]

The issue was numba going to 0.60.0 on June 13. I have now pinned it to 0.59.1, the prior version. We might want to instead put it as < 0.60.0.

[albop]

Hey @mnwhite, I'll have a look at what changed in numba recently and get back to you