title: class-validator case-insensitive enum validation?
body: <p>I have anum like this:</p>
  <pre><code>export enum UserRole {
    USER,
    ADMIN,
    BLOGGER
  }
  </code></pre>
  <p>and create.user.dto like this</p>
  <pre><code>import { IsEmail, IsEnum, IsNotEmpty, IsOptional } from 'class-validator';
  import { UserRole } from './user.entity';
  
  export class CreateUserDto {
    @IsEmail()
    email: string;
  
    @IsNotEmpty()
    firstName: string;
  
    @IsNotEmpty()
    lastName: string;
  
    @IsOptional()
    username: string;
  
    @IsOptional()
    @IsEnum(UserRole)
    role: UserRole;
  
    @IsNotEmpty()
    password: string;
  }
  </code></pre>
  <p>Now role validation does not fail if I only post the role uppercase('ADMIN','USER') or 'BLOGGER'.</p>
  <p>How to make class-validator not case sensitive? I mean, validate true also for 'admin' 'aDmIn'.</p>