feat: bump protoreflect to support optional fields in proto3

[aliellis]

Heyhey, just something I encountered recently

We have an old version of protoreflect which means that you receive an error when parsing proto3 files with optional fields, this was fixed with protobuf 3.1.5 when support for optional fields was provided by default

Steps to recreate

• Use latest version of kaf
• Try to consume a message with a proto3 schema that contains Optional field

example proto

syntax="proto3";

// Address is the home address of the user.
message Address {
  optional string hello = 1;
  string world = 2;

More information on the change can be found here

[birdayz]

thanks!