Filter volume trigger updates during fading states

When a sound player is in a FadeIn or FadeOut state, the volume is
constantly changing through scheduled ramp commands. Incoming volume
trigger events from the Sonos device during this time may report stale
values that don't match the appliance's internal state.

This change filters volume trigger updates when the appliance is in a
fading state (has is_fading=True), preventing the stale volume values
from updating the appliance state.

Note: This only filters incoming volume TRIGGERS (events from device).
Outgoing volume ramp COMMANDS (scheduled during fade) continue to be
sent normally via Command.make_msgs_from() which checks is_fading=True.

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

Author: majamassarini

soco_plugin/trigger/volume.py

@@ -29,6 +29,11 @@ def make_new_state_from(
         >>> d = soco_plugin.Description(msg)
         >>> new_state = trigger.make_new_state_from(d, old_state)
         """
+        # Skip volume updates when in fading state
+        # Volume is constantly changing during fade and incoming values may be stale
+        if hasattr(old_state, 'is_fading') and old_state.is_fading:
+            return old_state
+
         new_state = super(Trigger, self).make_new_state_from(
             another_description, old_state
         )