Add device: Ecowitt - wh31 (#4563)

Author: github-actions[bot]

library/library.json

@@ -12301,6 +12301,12 @@
             "manufacturer": "ZVIDAR",
             "model": "Z-CM-V01",
             "battery_type": "Rechargeable"
+        },
+        {
+            "manufacturer": "Ecowitt",
+            "model": "wh31",
+            "battery_type": "AA",
+            "battery_quantity": 2
         }
     ]
 }