Time varying risk premia

[jdebacker]

This PR allows the r_gov_scale and r_gov_shift parameters to vary over time. With this, one can model transitory shocks to the perceived risk of government debt (in a reduced form way since government default is not endogenous in OG-Core).

[codecov-commenter]

Codecov Report

Merging #852 (e4c2275) into master (ab92155) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #852   +/-   ##
=======================================
  Coverage   82.23%   82.24%           
=======================================
  Files          18       18           
  Lines        3985     3987    +2     
=======================================
+ Hits         3277     3279    +2     
  Misses        708      708           

Flag	Coverage Δ
unittests	82.24% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
ogcore/parameters.py	75.38% <ø> (ø)
ogcore/utils.py	90.65% <ø> (ø)
ogcore/SS.py	88.05% <100.00%> (ø)
ogcore/TPI.py	93.07% <100.00%> (ø)
ogcore/fiscal.py	100.00% <100.00%> (ø)

[jdebacker]

Test failure on the Windows runs has to do with Code Cov report not being able upload:

Error: Codecov: Failed to properly upload: The process 'D:\a\_actions\codecov\codecov-action\v3\dist\codecov.exe' failed with exit code 4294967295

I've had the same issue (which only affects Windows runs) on other PRs in other projects. Any ideas on this @rickecon? Should we just ignore?

[rickecon]

@jdebacker. I have gotten that error to go away sometimes by just rerunning the tests. I'll try that now.

[rickecon]

@jdebacker. The Setup Miniconda step does take a long time.

[rickecon]

Looks great. Thanks, @jdebacker. Merging.