title: error using simple kdeplot example from the doc
body: <p>I want to execute the following example from the doc in a jupyter notebook : <a href="https://seaborn.pydata.org/generated/seaborn.kdeplot.html" rel="nofollow noreferrer">https://seaborn.pydata.org/generated/seaborn.kdeplot.html</a></p>
  <pre><code>tips = sns.load_dataset(&quot;tips&quot;)
  sns.kdeplot(data=tips, x=&quot;total_bill&quot;, hue=&quot;time&quot;)
  </code></pre>
  <p>But I get an error :</p>
  <pre><code>ValueError: could not convert string to float: 'Sun'
  </code></pre>
  <p>I use seaborn 0.10.1 and python 3.8.3</p>
  <p>It works when I use :</p>
  <pre><code>tips = sns.load_dataset(&quot;tips&quot;)
  sns.kdeplot(data=tips.total_bill)
  </code></pre>
  <p>But in this case, I can't use hue with the time column.</p>