Fix call to plugins_with

Resolves: Can't locate object method "plugins_with" via package "Dist::Zilla::App::Command::listdeps" at /Users/ether/.perlbrew/libs/19.5@std/lib/perl5/Dist/Zilla/App/Command/listdeps.pm line 27, <DATA> line 123.

Clearly the listdeps command needs some tests ;)