test: upgrade chai to 5.x

[43081j]

Upgrades chai to the latest version (5.x) which now ships as ESM directly, meaning we no longer need esm-bundle's fork.

we may want to use node's built in test runner and assertion library for non-browser tests some day,

i also noticed we now have a mixture of uvu and chai - maybe we want to settle on one some day 🤔