Update device: 21 by ThermoBeacon (#1591)

Author: github-actions[bot]

custom_components/battery_notes/data/library.json

@@ -5251,6 +5251,11 @@
             "manufacturer": "Zooz",
             "model": "ZSE44",
             "battery_type": "CR2450"
+        },
+        {
+            "manufacturer": "ThermoBeacon",
+            "model": "21",
+            "battery_type": "CR2477"
         }
     ]
 }