build(deps): bump io.micronaut.test:micronaut-test-junit5

Bumps [io.micronaut.test:micronaut-test-junit5](https://github.com/micronaut-projects/micronaut-test) from 4.1.0 to 4.2.1.
- [Release notes](https://github.com/micronaut-projects/micronaut-test/releases)
- [Commits](micronaut-projects/micronaut-test@v4.1.0...v4.2.1)

---
updated-dependencies:
- dependency-name: io.micronaut.test:micronaut-test-junit5
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

server/jikkou-api-server/pom.xml

@@ -184,7 +184,7 @@
         <dependency>
             <groupId>io.micronaut.test</groupId>
             <artifactId>micronaut-test-junit5</artifactId>
-            <version>4.1.0</version>
+            <version>4.2.1</version>
             <scope>test</scope>
         </dependency>
         <dependency>