[flake8-errmsg] Exclude typing.cast from EM101

[danparizher]

Summary

Fixes #19596

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[ntBre]

Thanks! Just one small simplification suggestion and an idea for a follow-up, if you're interested.

[ntBre]

nit: this looks identical to the if-let below. Can we just add func to the destructuring there and return from inside the if?

It looks like this whole function would be nicer as a sequence of early returns:

let Expr::Call ... else return;
if checker.semantic().match_typing_expr(func, cast) return;
let Some(first) = args.first() else return;

but let's save that for a quick follow-up.