0.2.22 changes

[norrisjeremy]

• Add entry for 0.2.21 and update links for issues in prior releases.
• Add support for sntrup761x25519-sha512 KEX algorithm.
  -- As with [email protected], this requires Bouncy Castle.
• Add support for mlkem768x25519-sha256, mlkem768nistp256-sha256 & mlkem1024nistp384-sha384 KEX algorithms.
  -- As with sntrup761x25519-sha512 & [email protected], this requires Bouncy Castle.
  -- Once Alpine Linux 3.21 is released (hopefully later this year), we can switch Dockerfile.openssh99 over to using it instead of Alpine Linux Edge for the integration tests.
  -- Also, once JEP-496 is integrated into OpenJDK (hopefully for the Java 24 release due next year), we can then add an implementation of the ML-KEM KEX algorithms that doesn't rely on Bouncy Castle.
• Run tests on Java 23.

[sonarcloud]

Quality Gate failed

Failed conditions
15.6% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud

[norrisjeremy]

Quality Gate failed

Failed conditions 15.6% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud

Not sure what to do about this: I don't see much value in performing a bunch of refactoring to try and unify the ECDH+KEM & XEC+KEM implementations since the existing ECDH & XEC implementations are also similarly structured in the same way that SonarCloud seems to be objecting.