[REFACTOR] Update Tephi to follow MPL best practices

[ESadek-MO]

🔨 Refactor

Currently, Tephi uses outdated methods and interface, due to the fact it hasn't had much love over the last decade. The first priority is getting essential features out, and then after that I wish to refactor the code (keeping the UI identical as possible).

Some known outdated practices are listed below.

rcomer on Nov 15, 2024
I'm not sure that you can use allow_rasterization and also pass extra keywords to the draw method any more. C.f. SciTools/cartopy#2333.

Namedtuples could be replaced by dataclasses. The benefit is more futureproofing than any additionally needed functionailty. #170 (comment)

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[RachelNorth]

I'd appreciate tephi being modernised, but understand that the time scale may need to be a bit fluid...