Update to latest scala versions (#261)

* Update scala 2.12.6 to 2.12.8

* Update sbt-scalajs to 0.6.28

* Update scalatest to 3.0.8-RC5

* Update scala 2.13.0-RC2 to 2.13.0-RC3

.travis.yml

@@ -10,8 +10,8 @@ install:
 
 scala:
   - "2.11.12"
-  - "2.12.6"
-  - "2.13.0-RC2"
+  - "2.12.8"
+  - "2.13.0-RC3"
 
 jdk:
   - openjdk8

build.sbt

@@ -1,10 +1,10 @@
 import sbtcrossproject.CrossPlugin.autoImport.crossProject
 
 scalaVersion in ThisBuild := "2.11.12"
-crossScalaVersions in ThisBuild := Seq("2.11.12", "2.12.6", "2.13.0-RC2")
+crossScalaVersions in ThisBuild := Seq("2.11.12", "2.12.8", "2.13.0-RC3")
 scalaJSUseRhino in ThisBuild := true
 
-lazy val scalatest = "org.scalatest" %% "scalatest" % "3.0.8-RC4"
+lazy val scalatest = "org.scalatest" %% "scalatest" % "3.0.8-RC5"
 lazy val specs2 = "org.specs2" %% "specs2-core" % "4.5.1"
 
 val commonSettings = Defaults.coreDefaultSettings ++ Seq(

project/plugins.sbt

@@ -3,5 +3,5 @@ addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "2.3")
 //addSbtPlugin("com.jsuereth" % "sbt-pgp" % "2.0.0-M2")
 addSbtPlugin("com.typesafe.sbt" % "sbt-git" % "1.0.0")
 
-addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.27")
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.28")
 addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "0.6.0")