title: Python: Max date for each month from the list
body: <p>I have a list that contains date and the list looks like as follow:</p>
  <pre><code>list = ['2020-04-05',
   '2020-04-12',
   '2020-04-19',
   '2020-04-26',
   '2020-05-03',
   '2020-05-10',
   '2020-05-17',
   '2020-05-24',
   '2020-05-31',
   '2020-06-07',
   '2020-06-14',
   '2020-06-21',
   '2020-06-28',
   '2020-07-05',
   '2020-07-12',
   '2020-07-19',
   '2020-07-26',
   '2020-08-02',
   '2020-08-09',
   '2020-08-16',
   '2020-08-23',
   '2020-08-30',
   '2020-09-06',
   '2020-09-20',
   '2020-09-13']
  </code></pre>
  <p>I want to extract the highest date of each month from the list. My desired output looks like as follow:</p>
  <pre><code>Desired list = ['2020-04-26','2020-05-31','2020-06-28','2020-07-26','2020-08-30','2020-09-20']
  </code></pre>
  <p>I tried to find the max date of the month using <code>Max()</code> but it gave overall max date from the list. Is there any way of finding max date of each month from the list.</p>