Validacion de usuario en el formulario Login

forms.py

from django import forms
from django.contrib.auth import authenticate
#
from .models import User

class LoginForm(forms.Form):
    username = forms.CharField(
        label='username',
        required=True,
        widget=forms.TextInput(
            attrs={
                'placeholder': 'usernmae',
            }
        )
    )
    password = forms.CharField(
        label='Contraseña',
        required=True,
        widget=forms.PasswordInput(
            attrs={
                'placeholder': 'contraseña'
            }
        )
    )

    def clean(self):
        cleaned_data = super(LoginForm, self).clean()
        username = self.cleaned_data['username']
        password = self.cleaned_data['password']

        if not authenticate(username=username, password=password):
            raise forms.ValidationError('Los datos de usuario no son correctos')
        
        return self.cleaned_data

views.py

class LoginUser(FormView):
    template_name = 'users/login.html'
    form_class = LoginForm
    success_url = reverse_lazy('home_app:panel')

    def form_valid(self, form):
        user = authenticate(
            username=form.cleaned_data['username'],
            password=form.cleaned_data['password']
        )
        login(self.request, user)
        return super(LoginUser, self).form_valid(form)

urls.py

    path(
        'login/', 
        views.LoginUser.as_view(),
        name='user-login',
    ),