Make RC configurator thread local

[cvanelteren]

Attempt to fix the discrepancies between the tests by putting a read lock on the config properties.

[cvanelteren]

TODO: replace with copy-on-write

• added thread local rc params

[codecov]

Codecov Report

Attention: Patch coverage is 71.73913% with 52 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
ultraplot/config.py	69.07%	35 Missing and 12 partials ⚠️
ultraplot/internals/rcsetup.py	66.66%	5 Missing ⚠️

📢 Thoughts on this report? Let us know!

[cvanelteren]

Not sure if I am making the situation worse. The issue is I think generated by threads modifying rc values which causes issues with other tests.

The tests that we were initially failing are in particular moddifying the rc and causing issues. Will need to return to this as this has high priority now.

[beckermr]

I suspect that matplotlib itself would need to be thread safe in order for this to work. My guess is that it is not.

Maybe try an approach where we force a small subset of the tests to be done serially?

[cvanelteren]

That could indeed be the case, but I think the edits all go through this configurator object. This would mean that if we protect it, the matplotlib rc file would be protected too. I will go back now and check the thread safety as I was a bit hazzy when I looked at this last night.

[cvanelteren]

I need to separate the initialising of the colormaps before this can be fixed more to follow soon.