v1.12.0

• Add buf curl command to invoke RPCs via Connect,
  gRPC, or gRPC-Web
• Introduce objc_class_prefix option in managed mode, allowing a default value
  for objc_class_prefix for all files, except and override, which both behave
  similarly to other except and override options. Specifying an empty default
  value is equivalent to having managed mode on in previous versions.
• Introduce ruby_package option in managed mode, allowing except and override,
  in the same style as objc_class_prefix. Leaving ruby_package unspecified has
  the same effect as having mananged mode enabled in previous versions.