HeaderParams are parsed as object, not mutiple params

[Juhbaldissera]

Similar to #39

Having something like

class GetWishlistHeaderParams {
  @IsString()
  key: string;

  @IsString()
  deviceId: string;

  @IsString()
  deviceOs: string;

  @IsString()
  appVersion: string;

  @IsString()
  acceptLanguage: string;
}

#....
    @Get('/')
    public async getWishlist(@HeaderParams() headerParams: GetWishlistHeaderParams) {
}

Generates swagger with one header param of object type, instead of mutiple header params:

[epiphone]

Fixed in https://github.com/epiphone/routing-controllers-openapi/releases/tag/v5.0.1.