helpers/mailauth/tools: punycode is deprecated in Node 21+

[nykma]

// helpers/src/lib/mailauth/tools.ts:7
import punycode from "punycode";

Code above will throw an exception on (at least) Node21 env.

BTW, the dependency psl 1.9.0 meets the same issue: lupomontero/psl#315

Please consider use the alternative punycode npm package instead of the built-in one, and find an alternative of psl (or fork that, since it seems not maintained for a long time).