Remove unused imports

Author: Tabrizian

qa/L0_grpc/grpc_client_plugin_test.py

@@ -31,7 +31,6 @@
 sys.path.append("../common")
 
 import unittest
-from unittest.mock import AsyncMock, patch, MagicMock
 import numpy as np
 import test_util as tu
 import tritonclient.grpc as tritongrpcclient