fix: Unable to extends property title

[aweikalee]

import { IsOptional, Equals, ClassPropertyTitle, validator } from 'class-validator-multi-lang';

class Parent {
  @IsOptional()
  @Equals('test')
  @ClassPropertyTitle('property "title"')
  title: string = 'bad_value';
}

class MyClass extends Parent {}

const RU_I18N_MESSAGES = {
  '$property must be equal to $constraint1': '$property должно быть равно $constraint1',
};
const RU_I18N_TITLES = {
  'property "title"': 'поле "заголовок"',
};

const model = new MyClass();

validator.validate(model, { messages: RU_I18N_MESSAGES, titles: RU_I18N_TITLES }).then(errors => {
  console.log(errors[0].constraints);
  // now out: title должно быть равно test
  // expect out: поле "заголовок" должно быть равно test
});