title: Error in Django Widget tweaks 'render_field' tag requires a form field followed by a list of attributes and values in the form attr="value":
body: <p>I'm getting this error 
  'render_field' tag requires a form field followed by a list of attributes and values in the form attr="value":</p>
  
  <p>I'm trying to use Widget Tweaks for Django to render the Form. It gives the error and highlights the line <code>{% render_field field class ="form-control is-valid" %}</code> once the page loads on the browser</p>
  
  <pre><code>{% extends 'base.html' %}
  
  {% load widget_tweaks %}
  
  
  {% block title %}
  
  New Topic: {{board.name}} - {{board.super}}
  
  {% endblock %}
  
  {% block breadcrumb %}
          &lt;li class="breadcrumb-item"&gt;&lt;a href="{% url 'home' %}"&gt;Boards&lt;/a&gt;&lt;/li&gt;
          &lt;li class="breadcrumb-item"&gt;&lt;a href="{% url 'board_topics' board.pk %}"&gt;{{board.name}}&lt;/a&gt;&lt;/li&gt;
          &lt;li class="breadcrumb-item active"&gt;New Topic&lt;li&gt;
  {% endblock %}
  
      {% block content %}
  
     &lt;form method="post" novalidate &gt;
          {% csrf_token %}
  
         {% for field in form %}
  
             &lt;div class = "form-group" &gt;
  
                 {{field.label_tag}}
  
                 {% if form.is_bound %}
                      {% if field.errors %}
                          {% render_field field class="form-control is-invalid" %}
                          {% for error in field.errors %}
                              &lt;div class="invalid-feedback"&gt;
                                  {{error}}
                              &lt;/div&gt;
                          {% endfor %}
                      {% else %}
                          {% render_field field class ="form-control is-valid" %}
                      {% endif %}
                     {% else %}
                      {% render_field field class ="form-control" %}
                     {% endif %}
                     {% if field.help_text %}
                       &lt;small class="form-text text-muted" &gt;
                          {{ field.help_text }}
                       &lt;/small&gt;
                     {% endif %}
  
             &lt;/div&gt;
  
         {% endfor %}
          &lt;button type ="submit" class="btn btn-success"&gt;Post&lt;/button&gt;
  
      &lt;/form&gt;
  
      {% endblock %}
  
  This must render the form with bootstrap styles.
  </code></pre>