fix pandas 2.0 error

app.py

@@ -200,7 +200,7 @@ def full_report():
                               y='total_jumps', 
                               color='continent', 
                               template="plotly_dark")
-    
+    df.fillna(0, inplace=True)
     daily_df = df.groupby(['day']).sum().reset_index()
     per_day_plot = px.scatter(daily_df, x='day', y='jumps', 
                               trendline='rolling',