nicegui v3.8.0: XSS fix, cursor preservation, faster shutdowns v3.8.0

Shipped a security patch closing an XSS vulnerability in run_method() (breaking change: method names only, no arbitrary JS expressions now). Also fixed cursor position weirdness in codemirror, made shutdown ~1s faster by waking the outbox loop, and prevented crashes in prune_user_storage when UI elements get created before ui.run_with(). Check the changelog if you're using run_method() with JS functions, ngl.