Bump junit:junit from 4.12 to 4.13.1

Bumps [junit: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](https://github.com/junit-team/junit4/compare/r4.12...r4.13.1)

---
updated-dependencies:
- dependency-name: junit:junit
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/pom.xml b/pom.xml
index 6364f4f..818bd94 100644
--- a/pom.xml
+++ b/pom.xml
@@ -34,7 +34,7 @@
     <hamcrest.version>1.3</hamcrest.version>
     <jackson.version>2.9.5</jackson.version>
     <joda.version>2.4</joda.version>
-    <junit.version>4.12</junit.version>
+    <junit.version>4.13.1</junit.version>
     <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
     <maven-exec-plugin.version>1.6.0</maven-exec-plugin.version>
     <maven-jar-plugin.version>3.0.2</maven-jar-plugin.version>