[#472] Use JUnit 5 instead of JUnit 4

Version 64 of the parent POM will provide the dependency information
for JUnit 5. Therefore the entry in the dependency management section
can be removed if version 64 will be released.

pom.xml

@@ -98,7 +98,7 @@
   <properties>
     <mojo.java.target>1.8</mojo.java.target>
     <maven.compiler.source>${mojo.java.target}</maven.compiler.source>
-
+    <junitBomVersion>5.7.2</junitBomVersion>
     <mavenVersion>3.0.5</mavenVersion>
     <wagonVersion>3.4.0</wagonVersion>
     <doxiaVersion>1.9.1</doxiaVersion>
@@ -108,6 +108,18 @@
     <project.build.outputTimestamp>2020-08-07T21:31:00Z</project.build.outputTimestamp>
   </properties>
 
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>org.junit</groupId>
+        <artifactId>junit-bom</artifactId>
+        <version>${junitBomVersion}</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
   <dependencies>
     <dependency>
       <groupId>org.apache.maven.plugin-tools</groupId>
@@ -227,8 +239,13 @@
       <version>3.8.1</version>
     </dependency>
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.vintage</groupId>
+      <artifactId>junit-vintage-engine</artifactId>
       <scope>test</scope>
     </dependency>
     <dependency>