Bump junit from 4.13-beta-2 to 4.13.1 in /Java/AppEngine

Bumps [junit](https://github.com/junit-team/junit4) from 4.13-beta-2 to 4.13.1.
- [Release notes](https://github.com/junit-team/junit4/releases)
- [Changelog](https://github.com/junit-team/junit4/blob/main/doc/ReleaseNotes4.13.1.md)
- [Commits](https://github.com/junit-team/junit4/commits/r4.13.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Java/AppEngine/pom.xml

@@ -61,7 +61,7 @@
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
-      <version>4.13-beta-2</version>
+      <version>4.13.1</version>
       <scope>test</scope>
     </dependency>
     <dependency>