Plot GP dist test is flaky

[ricardoV94]

https://github.com/pymc-devs/pymc/actions/runs/4587854474/jobs/8190466483?pr=6635

[michaelosthege]

That's not special to plot_gp_dist - it fails in the line pyplot.subplots() (!)

https://github.com/pymc-devs/pymc/actions/runs/4587854474/jobs/8190466483?pr=6635#step:7:188

[ricardoV94]

Any idea why (and only sometimes)?

[michaelosthege]

No, I never saw it before, and I'm no expert in tkinter/matplotlib backends..

[QuLogic]

Since this is CI, I assume you don't actually need the interactivity. It would be best to set the backend to a non-interactive one, by setting the MPLBACKEND=Agg environment variable. Then you won't have to worry about Tk being broken.

[ricardoV94]

Sounds good @QuLogic, do you want to take a stab at it yourself?