Merge branch 'extend-plot_posterior_predictive_glm' of github.com:MarcoGorelli/pymc3 into extend-plot_posterior_predictive_glm

Author: MarcoGorelli

RELEASE-NOTES.md

@@ -5,6 +5,7 @@ This is the first release to support Python3.9 and to drop Python3.6.
 
 ### New Features
 - `OrderedProbit` distribution added (see [#4232](https://github.com/pymc-devs/pymc3/pull/4232)).
+- `plot_posterior_predictive_glm` now works with `arviz.InferenceData` as well (see [#4234](https://github.com/pymc-devs/pymc3/pull/4234))
 
 ### Maintenance
 - Fixed bug whereby partial traces returns after keyboard interrupt during parallel sampling had fewer draws than would've been available [#4318](https://github.com/pymc-devs/pymc3/pull/4318)