*/*: drop tty parameters.

The "tty" parameter for postgresql connections has been ignored for as
long as I can remember, but with postgresql-14, it has finally been
removed. Now, attempting to supply it causes an error:

  PG::ConnectionBad: invalid connection option "tty"

This commit removes all mention of the parameter, and updates two
instances where PG::Connection.new() was called with positional
arguments. Now it is called with a hash, sans the :tty key, which
should be backwards-compatible.