fix: avoid fatal warning in scaladoc-js

Author: hamzaremmal

scaladoc-js/main/src/Main.scala

@@ -1,7 +1,7 @@
 package dotty.tools.scaladoc
 import scala.scalajs.js.annotation._
 
-object Main extends App:
+@main def Main =
   Searchbar()
   DropdownHandler()
   TooltipNormalizer()