MT#8395 Drop unused dependency on libemail-send-perl

Dependency on libcatalyst-plugin-email-perl was removed already.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=748849 ->
libemail-send-perl was removed from unstable recently.

As libemail-send-perl is deprecated upstream, we should use
libemail-sender-perl instead and a dependency on
libemail-sender-perl was introduced already with git commit
1fd67eb3