text: Title: How to change a response timezone based on a query parameter?
  Body: Hi, I want to know how to change a response timezone based on a query parmeter like https:://example.com?timezone=utc , https://example.com?timezone=Asia/Tokyo ,or https://exampl.com?timezone=Asia/Kolkata? 
  
  I think  the answer of https://github.com/vitalik/django-ninja/issues/786 is related to this problem, 
  but  I can't understand how to change timezone dynamicaly.
  
  ```
  from ninja.renderers import JSONRenderer
  from ninja.responses import NinjaJSONEncoder
  
  
  class MyJsonEncoder(NinjaJSONEncoder):
      def default(self, o):
          if isinstance(o, datetime.datetime):
                 ###############################
                 #####how to set timezone dynamically? 
                 ##################################
                 return o.astimezone().isoformat()
          return super().default(o)
  
  class MyJsonRenderer(JSONRenderer):
     encoder_class = NinjaJSONEncoder
  
  api = NinjaAPI(renderer=MyJsonRenderer())
  ```