Remove IvyPlugin for requires

Author: Adrien Surée

src/main/scala/sbtlicensereport/SbtLicenseReport.scala

@@ -6,7 +6,7 @@ import license._
 
 /** A plugin which enables reporting on licensing used within a project. */
 object SbtLicenseReport extends AutoPlugin {
-  override def requires: Plugins = plugins.IvyPlugin
+  override def requires: Plugins = empty
   override def trigger = allRequirements
 
   object autoImportImpl {