title: Python xlwings - TypeError: must be real number, not Timedelta
body: <p>I have a pandas dataframe containing columns in timedelta64[ns] format.
  For this project I cannot use df.to_excel() and I need to import the dataframe via xlwings so that it prints into existing Excel Workbook and keeps its format.</p>
  <p>When I try the usual:</p>
  <pre><code>workbook_sablona_dochazka.sheets[zamestnanec].range('A1').options(index=False).value = individual_dochazka_zamestnanec
  </code></pre>
  <p>I receive error:
  TypeError: must be real number, not Timedelta</p>
  <p>Is there a way to format my timedelta64[ns] so that xlwings would be able to import the dataframe in? I need to preserve my time values so that it becomes 12:30:00 in Excel again after xlwings import and maybe some after-formatting inside the Excel itself.</p>
  <p>I tried:</p>
  <pre><code>individual_dochazka_zamestnanec['Příchod do práce'] = individual_dochazka_zamestnanec['Příchod do práce'].values.astype(float)
  </code></pre>
  <p>This worked around the error but imported columns had totally out of sense numbers.</p>
  <p>Any idea how to work around this?</p>
  <p>Thank you very much in advance!</p>