Upgrade to Hibernate Validator 6.2

[jhoeller]

Hibernate Validator 6.2 is in the release candidate stage now, probably GA in time for our 5.3.3 release.

[mkurz]

@jhoeller Why not Hibernate Validator 7.0? See https://hibernate.org/validator/releases/7.0/#whats-new

[jhoeller]

Hibernate Validator 7.0 is jakarta.validation based, 6.2 is the last javax.validation based line there. That aside, this is just about the version that we use for testing in our build. Generally speaking, we're still compatible with any javax.validation based provider.