Current py bitbox02 deps require protobuf >= 3.21, which is not compatible
with files generated by protoc < 3.19.
It seems that protobuf v3.20.x is compatible with files generated by
both protoc < 3.19 and >= 3.19. This commit relaxes the constraint to
protobuf version >= 3.20, to provide better compatibility.
Current py bitbox02 deps require protobuf >= 3.21, which is not compatible with files generated by protoc < 3.19. It seems that protobuf v3.20.x is compatible with files generated by both protoc < 3.19 and >= 3.19. This commit relaxes the constraint to protobuf version >= 3.20, to provide better compatibility.