TangoShutter: fix docstrings

Also changed type hint for `TangoShutter._update_value`.
The value could possibly be a string (i.e. using `TangoChannel` with
`read_as_str` set to True).

mxcubecore/HardwareObjects/TangoShutter.py

@@ -101,7 +101,7 @@ def init(self) -> None:
         self.state_channel.connect_signal("update", self._update_value)
         self.update_state()
 
-    def _update_value(self, value: DevState) -> None:
+    def _update_value(self, value: DevState | str) -> None:
         """Update the value.
         Args:
             value: The value reported by the state channel.
@@ -138,7 +138,7 @@ def _initialise_values(self) -> None:
     def get_state(self) -> HardwareObjectState:
         """Get the device state.
         Returns:
-            (enum 'HardwareObjectState'): Device state.
+            Device state.
         """
         try:
             _state = self.get_value().name
@@ -150,7 +150,7 @@ def get_state(self) -> HardwareObjectState:
     def get_value(self) -> TangoShutterStates:
         """Get the device value
         Returns:
-            (Enum): Enum member, corresponding to the 'VALUE' or UNKNOWN.
+            Enum member, corresponding to the 'VALUE' or UNKNOWN.
         """
         _val = str(self.state_channel.get_value())
         return self.value_to_enum(_val)