gschema: Fix gettext-domain

Author: piotrdrag

data/org.gnome.meld.gschema.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<schemalist>
+<schemalist gettext-domain="meld">
 
   <enum id="org.gnome.meld.mergefileorder">
     <value nick="local-merge-remote" value="0"/>