buildscript: switch to GTNewHorizons ForgeGradle of 1.2.3 version

build.gradle

@@ -31,7 +31,7 @@ buildscript {
         }
     }
     dependencies {
-        classpath 'com.github.TheElan:ForgeGradle:1.2.2'
+        classpath 'com.github.GTNewHorizons:ForgeGradle:1.2.3'
     }
 }