如何在django.contrib.auth.forms UserCreationForm中放置复选框

from django import forms
from django.contrib.auth.forms import UserCreationForm
from django.contrib.auth.models import User

class CustomUserCreationForm(UserCreationForm):
    is_admin = forms.BooleanField(required=False)

    class Meta:
        model = User
        fields = ('username', 'password1', 'password2', 'is_admin')

from django.shortcuts import render, redirect
from .forms import CustomUserCreationForm

def register(request):
    if request.method == 'POST':
        form = CustomUserCreationForm(request.POST)
        if form.is_valid():
            form.save()
            return redirect('home')
    else:
        form = CustomUserCreationForm()
    return render(request, 'registration/register.html', {'form': form})

<form method="POST">
  {% csrf_token %}
  {{ form.as_p }}
  <button type="submit">注册</button>
</form>