message: objc: Preparing for 1.2.0-rc4 release.
  GitOrigin-RevId:
diff: +Version 1.2.0-rc4
  +==================================
  +Added API to retrieve keyset handle with public keys only.
  +Dropped support for 192-bit keys for AES-GCM, AES-EAX and AES-CTR.
  +This is a pre-release version.
  +
  Version 1.2.0-rc3
  ==================================
  Added Swift-friendly initializers for TinkRegistryConfig.
  