Deal with JUnit 4 version no longer being inherited from alpine-parent

Alpine was migrated to JUnit Jupiter via stevespringett/Alpine#609 and thus no longer provides JUnit 4 versions.

Signed-off-by: Niklas <nscuro@protonmail.com>

pom.xml

@@ -104,6 +104,7 @@
         <lib.jackson-databind.version>2.17.1</lib.jackson-databind.version>
         <lib.json-java.version>20240303</lib.json-java.version>
         <lib.json-unit.version>3.4.1</lib.json-unit.version>
+        <lib.junit.version>4.13.2</lib.junit.version>
         <lib.lucene.version>8.11.3</lib.lucene.version>
         <lib.maven-artifact.version>3.9.8</lib.maven-artifact.version>
         <lib.mockserver-netty.version>5.15.0</lib.mockserver-netty.version>