v1.28.1

• The buf curl command has been updated to support the use of multiple schemas. This allows users to specify multiple --schema flags and/or to use both --schema and --reflect flags at the same time. The result is that additional sources can be consulted to resolve an element. This can be useful when the result of an RPC contains extensions or values in google.protobuf.Any messages that are not defined in the same schema that defines the RPC service.
• Fix issue where buf lint incorrectly reports error when (buf.validate.field).required is set for an optional field in proto3.