title: Django-taggit TaggableManager() producing Admin error
body: <p>I'm working through the book Django 2 By Example, in which I'm trying to build a blog application with tagging functionality. </p>
  
  <p>My code for including <code>django-taggit</code> (after installing version 0.22.2 with pip) is the following. </p>
  
  <p>Add the app to <code>INSTALLED_APPS</code>:</p>
  
  <pre><code>INSTALLED_APPS = [
      #...
      'blog.apps.BlogConfig',
      'taggit',
  ]
  </code></pre>
  
  <p>Add <code>TaggableManager</code> provided by <code>django-taggit</code> to <code>Post</code> model.</p>
  
  <pre><code>from django.db import models
  from django.utils import timezone
  from django.contrib.auth.models import User
  from django.urls import reverse
  from taggit.managers import TaggableManager
  # Create your models here.
  class PublishedManager(models.Manager):
      def get_queryset(self):
          return super(PublishedManager, self).get_queryset().filter(status='published')
  
  
  class Post(models.Model):
      STATUS_CHOICES = (
          ('draft', 'Draft'),
          ('published', 'Published'),
      )
      title = models.CharField(max_length=250)
      slug = models.SlugField(max_length=250, unique_for_date='publish')
      author = models.ForeignKey(User, on_delete=models.CASCADE, related_name='blog_posts')
      body = models.TextField(default='')
      publish = models.DateTimeField(default=timezone.now)
      created = models.DateTimeField(auto_now_add=True)
      updated = models.DateTimeField(auto_now=True)
      status = models.CharField(max_length=10, choices=STATUS_CHOICES, default='draft')
  
      objects = models.Manager() # The default manager.
      published = PublishedManager() # Our custom manager.
      tags = TaggableManager()
      def get_absolute_url(self):
          return reverse('blog:post_detail',
                         args=[self.publish.year,
                               self.publish.month,
                               self.publish.day,
                               self.slug])
      class Meta:
          ordering = ('publish',)
  
      def __str__(self):
          return self.title
  </code></pre>
  
  <p>When I add the line <code>tags = TaggableManager()</code> to the <code>Post</code> model, I get the following error when trying to add a new post or edit an existing post via the admin site:</p>
  
  <p><code>TypeError: render() got an unexpected keyword argument 'renderer'</code>.</p>
  
  <p>I have no idea why this error is being generated, so any advice would be greatly appreciated.</p>