chore: remove unused mockserver-netty test dependency

[leehaut]

Summary

• Drop unused org.mock-server:mockserver-netty 5.15.0 from the parent POM (mockserver.version, dependencyManagement, and the inherited test dependency).
• The only usage was WebStreamReadTest, which mocked a remote .xlsx URL. That test and web/io.xlsx were removed in refactor(examples): Fesod Examples Module Refactoring #770 when examples were refactored
• This also removes transitive BouncyCastle 1.72 findings: CVE-2024-29857, CVE-2024-30172, CVE-2024-34447, and CVE-2024-30171. MockServer 6+/7.x cannot be used here because it requires Java 17, while this project still tests on JDK 8.

[delei]

LGTM