support "optional" fields in protoc3

[stonerxs]

problem:
is a protoc3 file that contains optional fields, but code generator protoc-gen-gorm hasn't been updated to support optional fields in protoc3. Please ask the owner of this code generator to support protoc3 optional.--gorm_out:

Now proto3 has begun to support the optional feature. When will protoc Gen Gorm start to support it?

[RomanSter]

Same issue, but in their examples they do have optional fields..

protoc-gen-gorm/example/user/user.proto

Line 56 in 76a99c1

optional string address_2 = 3;

[RomanSter]

was solved, make sure you protoc is the right version
#250