Update reshape-data-pivot.py3

Author: kamyu104

Python3/reshape-data-pivot.py3

@@ -6,4 +6,4 @@ import pandas as pd
 
 # pandas
 def pivotTable(weather: pd.DataFrame) -> pd.DataFrame:
-    return df.pivot(index="month", columns="city", values="temperature")
+    return weather.pivot(index="month", columns="city", values="temperature")