fix(sim positioner): do not emit values within tolerance limit

ophyd_devices/sim/sim_positioner.py

@@ -146,8 +146,12 @@ class SimPositioner(Device, PositionerBase):
     def _update_state(self, val):
         """Update the state of the simulated device."""
         old_readback = self._get_sim_state(self.readback.name)
+
         self._set_sim_state(self.readback.name, val)
 
+        if np.isclose(old_readback, val, atol=self.tolerance.get()):
+            return
+
         # Run subscription on "readback"
         self._run_subs(
             sub_type=self.SUB_READBACK,