title: Pandas date_range to generate monthly data at beginning of the month
body: <p>I'm trying to generate a date range of monthly data where the day is always at the beginning of the month:</p>
  
  <pre><code>pd.date_range(start='1/1/1980', end='11/1/1991', freq='M')
  </code></pre>
  
  <p>This generates <code>1/31/1980</code>, <code>2/29/1980</code>, and so on. Instead, I just want <code>1/1/1980</code>, <code>2/1/1980</code>,...</p>
  
  <p>I've seen other question ask about generating data that is always on a specific day of the month, with answers saying it wasn't possible, but beginning of month surely must be possible!</p>