mpris: use a Unicode en dash where apropriate
mpris: use a Unicode en dash where apropriate

Skipped 'use utf8' as it causes Perl to misinterpret metadata obtained
from the player, and I'm too lazy to scatter utf8::decode() everywhere.

grawity/hacks,grawity/hacks,grawity/hacks,grawity/hacks,grawity/hacks,grawity/hacks,grawity/hacks