Quiero una validación en mi modelo Django para que el campo de pregunta no acepte un número entero. Intenté hacerlo pero no está funcionando. ¿Cómo puedo hacerlo?

Aquí está mi código

models.py

from django.db import models

class Question(models.Model):
question = models.CharField(max_length=200, null= True)
option1 = models.CharField(max_length= 200, null= True)
option2 = models.CharField(max_length= 200, null= True)
option3 = models.CharField(max_length= 200, null= True)
option4 = models.CharField(max_length= 200, null= True)
answer = models.CharField(max_length=200, null=True)

def __str__(self):
    return self.question

views.py

from django.shortcuts import render,redirect
from .models import *
from .forms import QuestionForm
from django.views import View
from django.urls import reverse

class AddQuestion(View):

def post(self, request):
    forms = QuestionForm(request.POST)
    if forms.is_valid():
        forms.save()
        print("estaba en If")
        return redirect(reverse('home'))
    else:
        print("estaba en else")
        context = {'forms': forms}
        return render(request, 'file/addQuestion.html', context)

def get(self, request):
    forms = QuestionForm()
    context = {'forms': forms}
    return render(request,'file/addQuestion.html',context)