Remove Drop bound from Task trait

[siku2]

Description

Rust now emits a warning for Drop bounds. This PR simply removes it from the Task trait and updates the documentation. A type implementing Task doesn't necessarily need to implement Drop itself to fulfil the invariant. Especially with web-sys / glee types that already clean up when dropped there's no need for the task itself to implement Drop as well.

I also removed the long redundant to_ms function and made it so the methods panic instead of truncating when duration is too big. This technically makes this a breaking change but I'm 99% sure that no one is currently relying on this behaviour :D

Checklist

• I have run cargo make pr-flow
• I have reviewed my own code

[jstarry]

glee

sounds more fun than gloo, shall we change it? 😉

[siku2]

Ah whoops, gloo is such a good play on "glue" (at least I hope that's what it is 😅) and I still manage to confuse it with a TV show I never even watched 😞