Update sbt-assembly to 0.15.0 in 0.11.x (#1870)

Author: scala-steward

project/plugins.sbt

@@ -1,6 +1,6 @@
 val scalaJSVersion = Option(System.getenv("SCALAJS_VERSION")).getOrElse("1.16.0")
 
-addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.10")
+addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.15.0")
 
 addSbtPlugin("com.github.sbt" % "sbt-pgp" % "2.3.1")