code: def update_template_version(
          self,
          name,
          subject,
          template_id,
          version_id,
          text='',
          html=None,
          timeout=None
      ):
          
          if(html):
              payload = {
                  'name': name,
                  'subject': subject,
                  'html': html,
                  'text': text
              }
          else:
              payload = {
                  'name': name,
                  'subject': subject,
                  'text': text
              }
  
          return self._api_request(
              self.TEMPLATES_VERSION_ENDPOINT % (template_id, version_id),
              self.HTTP_PUT,
              payload=payload,
              timeout=timeout
          )
docs: API call to update a template version