Add Scala 2.13.0-M4 support

- upgrade Scala version from 2.13.0-M3 to 2.13.0-M4 in `build.sbt` and `.travis.yml`

- upgrade scalatest version from 3.0.5-M1 to 3.0.6-SNAP1
- upgrade stala-xml version from 1.0.6 to 1.1.0

- additionally upgrade Scala 2.12.x version from 2.12.4 to latest 2.12.6 in `build.sbt` and `.travis.yml`

Author: gslowikowski

.travis.yml

@@ -9,8 +9,8 @@ jdk:
 scala:
   - 2.10.7
   - 2.11.12
-  - 2.12.4
-  - 2.13.0-M3
+  - 2.12.6
+  - 2.13.0-M4
 
 before_cache:
   - find "$HOME/.sbt/" -name '*.lock' -print0 | xargs -0 rm

build.sbt

@@ -7,12 +7,12 @@ import sbtcrossproject.CrossType
 
 val Org = "org.scoverage"
 val MockitoVersion = "2.19.0"
-val ScalatestVersion = "3.0.5-M1"
+val ScalatestVersion = "3.0.6-SNAP1"
 
 val appSettings = Seq(
     organization := Org,
-    scalaVersion := "2.12.4",
-    crossScalaVersions := Seq("2.10.7", "2.11.12", "2.12.4", "2.13.0-M3"),
+    scalaVersion := "2.12.6",
+    crossScalaVersions := Seq("2.10.7", "2.11.12", "2.12.6", "2.13.0-M4"),
     fork in Test := false,
     publishMavenStyle := true,
     publishArtifact in Test := false,
@@ -91,7 +91,7 @@ lazy val plugin = Project("scalac-scoverage-plugin", file("scalac-scoverage-plug
   )).settings(libraryDependencies ++= {
     CrossVersion.partialVersion(scalaVersion.value) match {
       case Some((2, scalaMajor)) if scalaMajor > 10 => Seq(
-        "org.scala-lang.modules" %% "scala-xml" % "1.0.6",
+        "org.scala-lang.modules" %% "scala-xml" % "1.1.0",
         "com.typesafe.scala-logging" %% "scala-logging" % "3.9.0" % "test"
       )
       case _ => Seq(