systemd-unit: Set LANG

Things like gnome-terminal require an UTF-8 locale and although we
expect gnome-session to set this up it's better to have a UTF-8 locale
right away.

debian/phosh.service

@@ -25,6 +25,7 @@ Before=graphical.target
 ConditionPathExists=/dev/tty0
 
 [Service]
+Environment=LANG=C.UTF-8
 ExecStart=/usr/bin/phosh
 TimeoutStartSec=60
 User=purism