title: Rasa Core: utter_template() missing 1 required positional argument: 'tracker'
body: <p>I am using Rasa core v10.2, with custom actions,  but getting <code>utter_template() missing 1 required positional argument: 'tracker'</code> error on the run function.</p>
  
  <p><strong>Custom action file: (actions.py)</strong></p>
  
  <pre><code>from rasa_core.actions import Action
  from rasa_core.events import SlotSet
  
  class searchJob(Action):
      def name(self):
          return 'action_search'
  
      def run(self, dispatcher, tracker, domain):
          return [SlotSet("jobsname", "as_aggregate")]
  </code></pre>
  
  <p><strong>domain.yml:</strong></p>
  
  <pre><code>slots:
    jobsname:
      type: text
  
  templates:
   utter_answer:
      - text: "The required jobs are {jobsname}"
  </code></pre>
  
  <p>Stories:</p>
  
  <pre><code>* search
    - action_search
    - utter_answer
  </code></pre>
  
  <p>The output is <code>[{'recipient_id': 'default', 'text': 'The required jobs are None'}]</code> which means the Slot it not set. Could the error message be the cause of it?</p>
  
  <p>Thank you.</p>