Advanced server certificate validation referencing obsolete methods

[lucasnodine]

This page: https://www.npgsql.org/doc/security.html?tabs=tabid-1#ssl-negotiation appears to reference this method https://www.npgsql.org/doc/api/Npgsql.NpgsqlDataSourceBuilder.html#Npgsql_NpgsqlDataSourceBuilder_UseUserCertificateValidationCallback_
which is obsolete.

Encountered this while trying to figure out how to update our code and still trying. Hoping this helps someone else.