Fix frontend freeze due to modbus device not responding (#49651)

Changing the timeout from package default, secures SENDING will
timeout, and after 3 retries break off.

Remark: this commit is tested with pymodbus v2.5.1 the old version
v2.3.0 have several problems in this area.
self._value = await self.async_get_last_state()

pymodbus v2.5.1 is active on DEV (bumped in an earlier PR).

homeassistant/components/modbus/modbus.py

@@ -3,6 +3,7 @@ import logging
 import threading
 
 from pymodbus.client.sync import ModbusSerialClient, ModbusTcpClient, ModbusUdpClient
+from pymodbus.constants import Defaults
 from pymodbus.exceptions import ModbusException
 from pymodbus.transaction import ModbusRtuFramer
 
@@ -138,6 +139,7 @@ class ModbusHub:
         self._config_timeout = client_config[CONF_TIMEOUT]
         self._config_delay = 0
 
+        Defaults.Timeout = 10
         if self._config_type == "serial":
             # serial configuration
             self._config_method = client_config[CONF_METHOD]