Change entity_timers to be a local variable. (#55258)

Ensure outstanding pymodbus calls are handled before closing.

homeassistant/components/modbus/modbus.py

@@ -189,13 +189,12 @@ class ModbusHub:
 
     name: str
 
-    entity_timers: list[CALLBACK_TYPE] = []
-
     def __init__(self, hass, client_config):
         """Initialize the Modbus hub."""
 
         # generic configuration
         self._client = None
+        self.entity_timers: list[CALLBACK_TYPE] = []
         self._async_cancel_listener = None
         self._in_error = False
         self._lock = asyncio.Lock()
@@ -294,6 +293,7 @@ class ModbusHub:
             call()
         self.entity_timers = []
         if self._client:
+            async with self._lock:
                 try:
                     self._client.close()
                 except ModbusException as exception_error: