net/ruby-net-pop: add version 0.1.2

devel/ruby-redmine51 require net-imap gem version 0.1.2 but ruby31 bundles
0.1.1.  So, it add latest version of net-pop gem 0.1.2 as ruby-net-pop.

No version change from deleted ruby-net-pop pacakge.

# Net::POP3

This library provides functionality for retrieving
email via POP3, the Post Office Protocol version 3. For details
of POP3, see [RFC1939] (http://www.ietf.org/rfc/rfc1939.txt).

(taca)