remove develop-requires prereq on MooseX::AttributeHelpers

This is still technically required for authors, but removing it from the
formal prereq list will get it out of
https://metacpan.org/requires/distribution/MooseX-AttributeHelpers?sort=[[2,1]]

dist.ini

@@ -20,9 +20,6 @@ namespace::autoclean = 0.08
 remove = MooseX::AttributeHelpers
 remove = MooseX::Role::WithOverloading
 
-[Prereqs / DevelopRequires]
-MooseX::AttributeHelpers = 0
-
 [MetaResources]
 x_IRC = irc://irc.perl.org/#moose
 x_MailingList = http://lists.perl.org/list/moose.html