fix(test): Add ClassVar annotations to modbus tests

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: osom8979

tester/modbus/test_function_codes.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 
 import time
+from typing import ClassVar
 from unittest import TestCase, main
 
 from cvp.modbus.client import ModbusTcpClient
@@ -9,6 +10,9 @@
 
 
 class TestFunctionCodes(TestCase):
+    datastore: ClassVar[ModbusDataStore]
+    server: ClassVar[ModbusTcpServer]
+
     @classmethod
     def setUpClass(cls) -> None:
         cls.datastore = ModbusDataStore()

tester/modbus/test_server_client.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 
 import time
+from typing import ClassVar
 from unittest import TestCase, main
 
 from cvp.modbus.client import ModbusTcpClient
@@ -9,6 +10,9 @@
 
 
 class TestServerClientIntegration(TestCase):
+    datastore: ClassVar[ModbusDataStore]
+    server: ClassVar[ModbusTcpServer]
+
     @classmethod
     def setUpClass(cls) -> None:
         cls.datastore = ModbusDataStore()