fix string error

app.py

@@ -35,7 +35,8 @@ def get_current_time_in_timezone(timezone: str) -> str:
 
 
 @tool
-def fibonacci(n: int) -> str:
+def fibonacci(n: str) -> str:
+    n = int(n)
     if n <= 0:
         return "Input should be a positive integer."
     elif n == 1: