Update app.py

app.py

@@ -17,7 +17,8 @@ class SalaryTracker:
         self.salary += amount
 
     def update_data(self, transaction):
-        self.data = self.data.append({'Transaction': transaction, 'Salary': self.salary}, ignore_index=True)
+        new_data = pd.DataFrame({'Transaction': [transaction], 'Salary': [self.salary]})
+        self.data = pd.concat([self.data, new_data], ignore_index=True)
 
     def generate_report(self):
         return self.data