Fix datetime function

cloud/app.py

@@ -317,7 +317,7 @@ def telemetry():
         return jsonify({"error": "Expected a JSON object/dictionary"}), 400
 
     # Stamp UTC timestamp for Node-RED queries
-    data["received_at"] = datetime.now(datetime.timezone.utc).isoformat()
+    data["received_at"] = datetime.now(timezone.utc).isoformat()
 
     try:
         telemetry_collection.insert_one(data)