Migrate WhoIs calls to non-blocking async variants

[JuxhinDB]

Currently WhoIs lookup is blocking which causes problems when trying to scale the functionality to hundreds of concurrent requests.

https://github.com/JuxhinDB/twistrs/blob/1f359b5797937115a511847954b5b033cd1bdc22/twistrs/src/enrich.rs#L357-L371

Should take a look at the whois_rust crate and see if it's possible to refactor this to an async call - https://docs.rs/whois-rust/latest/whois_rust/#asynchronous-apis

[nix2intel]

Would rdap be more forward looking now that cert validation via whois is being deprecated?

[JuxhinDB]

@nix2intel totally. For Have I Been Squatted we cascade this - we try RDAP first and then fallback to WHOIS if unavailable. That said, related to #70, I wouldn't include this in the library at all.