Update to ScalaTest version 3.0.1

* `pom.xml`
  * `scalatest.version` is now set to `3.0.1`
* `src/test/scala/org/scalatest/tools/maven/PluginTest.scala`
  * `ShouldMatchers` is no longer in 3.0.1, updated to use `Matchers`.

Author: isomarcte

pom.xml

@@ -19,7 +19,7 @@
     <scala.major.version>2.11</scala.major.version>
     <scala.minor.version>7</scala.minor.version>
     <scala.version>${scala.major.version}.${scala.minor.version}</scala.version>
-    <scalatest.version>2.2.6</scalatest.version>
+    <scalatest.version>3.0.1</scalatest.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <build.timestamp>${maven.build.timestamp}</build.timestamp>

src/test/scala/org/scalatest/tools/maven/PluginTest.scala

@@ -1,15 +1,19 @@
 package org.scalatest.tools.maven
 
 import java.io.File
-import org.scalatest.matchers.ShouldMatchers
+import org.scalatest.Matchers
 import org.scalatest.junit.JUnit3Suite
 import java.util.ArrayList
 import org.scalatest.BeforeAndAfterAll
 
 /**
  * @author Jon -Anders Teigen
  */
-class PluginTest extends JUnit3Suite with ShouldMatchers with PluginMatchers with BeforeAndAfterAll {
+final class PluginTest
+    extends JUnit3Suite
+    with BeforeAndAfterAll
+    with Matchers
+    with PluginMatchers {
   val tmpDir = new File(System.getProperty("java.io.tmpdir"))
   val reportsDirectory = new File(tmpDir, "reportsDirectory")
   val baseDir = new File(tmpDir, "basedir");