title: Is there a way to convert datetime to acceptable format?
body: <p>I have a program that predicts stock market with ETNA (Tinkoff's repository)</p>
  <pre><code>train_ts, test_ts = ts.train_test_split(train_start='2021-05-30',
                                      train_end='2022-04-30',
                                      test_start='2022-05-08',
                                      test_end='2022-05-30')
  </code></pre>
  <p>I am trying to actualise programm for each day by using
  'today = datetime.today()'
  but when i have an error</p>
  <p>TypeError: cannot do slice indexing on DatetimeIndex with these indexers [today] of type str</p>
  <p>how to convert &quot;today&quot; to an acceptable format?
  Maybe you can suggest better ways to do what i want. As i undersatnd i can't use today with strptime</p>