Add Java 21 JVMs to jvms.json

[tsmock]

I made a PR here: #556

Unfortunately, due to the CLA requirement, I have closed that PR.

Current vendors already in jvms.json that have Java 21 releases:

• Azul Zulu
• Bellsoft Liberica

Vendors that have delays on the Java 21 release:

• Eclipse Temurin -- see https://adoptium.net/blog/2023/09/temurin21-delay/

[tsmock]

Fixed in v1.9.0