Update sbt-scalajs, scalajs-compiler, ... to 0.6.26

Author: scala-steward

project/plugins.sbt

@@ -6,7 +6,7 @@ else
   Seq(addSbtPlugin("com.typesafe.sbt" % "sbt-osgi" % "0.9.3"))
 
 val scalaJSVersion =
-  Option(System.getenv("SCALAJS_VERSION")).filter(_.nonEmpty).getOrElse("0.6.25")
+  Option(System.getenv("SCALAJS_VERSION")).filter(_.nonEmpty).getOrElse("0.6.26")
 
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % scalaJSVersion)
 addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "0.6.0")