Update app.py

app.py

@@ -8,7 +8,7 @@ import os
 # client = pymongo.MongoClient("mongodb://localhost:27017/")
 # db = client["todo_db"]
 
-uri = environ.get("mongo_uri", None)
+uri = os.environ.get("mongo_uri", None)
 # Create a new client and connect to the server
 client = pymongo.MongoClient(uri, server_api=ServerApi('1'))
 db = client["todo_db"]