Removed mixin refmap as it is no longer needed.

build.gradle

@@ -30,7 +30,7 @@ java {
 }
 
 minecraft {
-    mappings channel: mapping_channel, version: "$mapping_version-$minecraft_version"
+    mappings channel: mapping_channel, version: "$mapping_version"
 
     copyIdeResources = true
     // generateRunFolders = true
@@ -72,8 +72,6 @@ minecraft {
 }
 
 mixin {
-    add sourceSets.main, "${mod_id}.refmap.json"
-
     config "${mod_id}.mixins.json"
 }