Don't cache device label

Generating the device label doesn't require much computing power. Thus,
caching does more harm than good, as it may return stale labels after
name changes. Now a fresh label is always generated.

netbox/dcim/models/devices.py

@@ -1069,7 +1069,7 @@ class Device(
             device.location = self.location
             device.save()
 
-    @cached_property
+    @property
     def label(self):
         """
         Return the device name if set; otherwise return a generated name if available.