Resolve plugin dependencies from maven central. (FabricMC#138)

Author: modmuss50

settings.gradle

@@ -4,6 +4,7 @@ pluginManagement {
             name = 'Fabric'
             url = 'https://maven.fabricmc.net/'
         }
+        mavenCentral()
         gradlePluginPortal()
     }
 }