feat: ensure taskhubgrpcclient expose .close() method for clients to pass down a close call to durabletask

Signed-off-by: Casper Nielsen <casper@diagrid.io>

Author: CasperGN

ext/dapr-ext-workflow/dapr/ext/workflow/dapr_workflow_client.py

@@ -277,3 +277,7 @@ def purge_workflow(self, instance_id: str, recursive: bool = True):
             recursive: The optional flag to also purge data from all child workflows.
         """
         return self.__obj.purge_orchestration(instance_id, recursive)
+
+    def close(self):
+        """Closes the gRPC connection used by the client."""
+        return self.__obj.close()