Update scala 2.13.0-RC1 to 2.13.0-RC2

Author: Philippus

Diff for: .travis.yml

@@ -6,7 +6,7 @@ jdk:
 scala:
   - 2.11.12
   - 2.12.8
-  - 2.13.0-RC1
+  - 2.13.0-RC2
 
 env:
   global:

Diff for: build.sbt

@@ -1,7 +1,7 @@
 import ScalaModulePlugin._
 import sbtcrossproject.CrossPlugin.autoImport.crossProject
 
-crossScalaVersions in ThisBuild := List("2.12.8", "2.11.12", "2.13.0-RC1")
+crossScalaVersions in ThisBuild := List("2.12.8", "2.11.12", "2.13.0-RC2")
 
 lazy val root = project.in(file("."))
   .aggregate(`scala-parser-combinatorsJS`, `scala-parser-combinatorsJVM`, `scala-parser-combinatorsNative`)