hotfix: datasource refresh

Closes #1553

Datasource refresh expects empty requests.

Author: jorwoods

tableauserverclient/server/endpoint/datasources_endpoint.py

@@ -190,7 +190,8 @@ def update_connection(
     def refresh(self, datasource_item: DatasourceItem, incremental: bool = False) -> JobItem:
         id_ = getattr(datasource_item, "id", datasource_item)
         url = f"{self.baseurl}/{id_}/refresh"
-        refresh_req = RequestFactory.Task.refresh_req(incremental)
+        # refresh_req = RequestFactory.Task.refresh_req(incremental)
+        refresh_req = RequestFactory.Empty.empty_req()
         server_response = self.post_request(url, refresh_req)
         new_job = JobItem.from_response(server_response.content, self.parent_srv.namespace)[0]
         return new_job