public async Task<User> RegistrateUser(User user)
 {
     if (user != null)
     {
         _dbContext.Users.Add(user);
         await _dbContext.SaveChangesAsync();
         return user;
     }
     return null;
 }
 public async Task<User> ValidateUser(User user)
 {
     var findedUser = await _dbContext.Users.FirstOrDefaultAsync(r => r.Surname == user.Surname
                                                     && r.Password == user.Password);
     return findedUser;
 }