fix: properly encode unicode codepoints outside BMP

[MineRobber9000]

The BMP (Basic Multilingual Plane) consists of all Unicode codepoints from U+0000 to U+FFFF. For characters in the BMP, you can encode them with a \uXXXX escape in both JSON and SNBT. However, characters outside of the BMP are encoded differently. In SNBT, you can use \Uxxxxxxxx (\U followed by 8 hex characters); in JSON, you need to encode them as UTF-16 surrogates. With this change, mecha can now properly encode these characters.

Fixes #496.

[rx-dev]

https://github.com/TheShulkerBox/shulker/blob/main/src/game/duels/instance.bolt#L40-L48

tried with this with a fork, didn't seem to change anything

team add duels.team_1 "Duels Team 1"
team add duels.team_2 "Duels Team 2"
team modify duels.team_1 friendlyFire false
team modify duels.team_1 prefix "\u1f5e1 "
team modify duels.team_1 seeFriendlyInvisibles false
team modify duels.team_2 friendlyFire false
team modify duels.team_2 prefix "\u1f5e1 "
team modify duels.team_2 seeFriendlyInvisibles false

[MineRobber9000]

It works on my end? Make sure you're installing specifically mecha from the fork (pip install C:\path\to\beet\packages\mecha).