build(deps-dev): bump org.testcontainers:mockserver (#319)

Bumps [org.testcontainers:mockserver](https://github.com/testcontainers/testcontainers-java) from 1.20.4 to 1.21.4.
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.20.4...1.21.4)

---
updated-dependencies:
- dependency-name: org.testcontainers:mockserver
  dependency-version: 1.21.4
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

lyo-client-samples/pom.xml

@@ -324,7 +324,7 @@
     <dependency>
       <groupId>org.testcontainers</groupId>
       <artifactId>mockserver</artifactId>
-      <version>1.20.4</version>
+      <version>1.21.4</version>
       <scope>test</scope>
     </dependency>