buildscript: upgrade ForgeGradle to 1.2.4

build.gradle

@@ -31,7 +31,7 @@ buildscript {
         }
     }
     dependencies {
-        classpath 'com.github.GTNewHorizons:ForgeGradle:1.2.3'
+        classpath 'com.github.GTNewHorizons:ForgeGradle:1.2.4'
     }
 }