Bump junit from 4.12 to 4.13.1 (#34)

Bumps [junit](https://github.com/junit-team/junit4) from 4.12 to 4.13.1.
- [Release notes](https://github.com/junit-team/junit4/releases)
- [Changelog](https://github.com/junit-team/junit4/blob/main/doc/ReleaseNotes4.12.md)
- [Commits](junit-team/junit4@r4.12...r4.13.1)

Author: dependabot[bot]

pom.xml

@@ -11,7 +11,7 @@
 
     <properties>
         <kafka.version>2.4.1</kafka.version>
-        <junit.version>4.12</junit.version>
+        <junit.version>4.13.1</junit.version>
         <sonar.projectKey>scalyr_kafka-connect-scalyr</sonar.projectKey>
         <sonar.organization>scalyr</sonar.organization>
         <sonar.host.url>https://sonarcloud.io</sonar.host.url>