title: pd.date_range for 9am each day between two pd.Timestamp objects
body: <p>What I have:</p>
  <pre><code>pd.Timestamp('2021-07-05 08:10:11')
  pd.Timestamp('2021-07-07 12:13:14')
  </code></pre>
  <p>What I'm looking for:</p>
  <pre><code>[pd.Timestamp('2021-07-05 09:00:00'), 
   pd.Timestamp('2021-07-06 09:00:00'), 
   pd.Timestamp('2021-07-07 09:00:00')]
  </code></pre>
  <p>It feels like I should be able to do this with some combination of of <code>pd.date_range</code> and <code>pd.offsets</code>, but I can't find the right combination.</p>
  <p>Given that 9am is the standard meteorological time point, I'm hoping someone has a nice solution for this already!</p>