chore: bump version to 1.12.4

Author: actionless

packaging/com.github.themix_project.Oomox.appdata.xml

@@ -15,7 +15,7 @@
           <image>https://raw.githubusercontent.com/themix-project/oomox/master/screenshots/pokedex_dawn.png</image>
       </screenshot>
   </screenshots>
-  <release date="2019-07-29" version="1.12.3"/>
+  <release date="2019-09-21" version="1.12.4"/>
   <url type="homepage">https://github.com/themix-project/oomox</url>
   <content_rating type="oars-1.0">
     <content_attribute id="violence-cartoon">none</content_attribute>