Maven 3.9.13 includes test dependencies in the binary distribution:

• plexus-testing-2.1.0.jar
• junit-jupiter-api-5.14.2.jar
• junit-platform-commons-1.14.2.jar
• apiguardian-api-1.1.2.jar
• opentest4j-1.3.0.jar

Root cause: missing <scope>test</scope> on the plexus-testing dependency in maven-core/pom.xml, introduced in 87408ac (#11547).

Fix: add <scope>test</scope> to the dependency.

See discussion on dev@maven: https://lists.apache.org/thread/53hjts7xcr2op33dobp554x9t1b94q20