Alternatives to update rows

I have the following sample data:

|      | date   | value |
|:---- |:------:| -----:|
|   0  | 2021/05|  50   |
|   1  | 2021/06|  60   |
|   2  | 2021/07|  70   |
|   3  | 2021/08|  80   |
|   4  | 2021/09|  90   |
|   5  | 2021/10|  100  |

I want to update the data in the 'date' column, where for example '2021/05' becomes '05/10/2021', '2021/06' becomes '06/12/2021' and so long (I have to choose the new date manually for every row).

Is there a better/more clever way to do it instead of:

for i in df.index:
    if df['date'][i] == '2021/05':
        df['date'][i] = '05/10/2021'
    elif df['date'][i] == '2021/06':
        df['date'][i] = '06/12/2021'

The problem is that there are more than hundred rows that have to be updated and the code above will be tremendously long.