title: Change tick size on colorbar of seaborn heatmap
body: <p>I want to increase the tick label size corresponding to the colorbar in a heatmap plot created using the <code>seaborn</code> module. As an example:</p>
  
  <pre><code>import seaborn as sns
  import pandas as pd
  import numpy as np
  
  arr = np.random.random((3,3))
  df = pd.DataFrame(arr)
  ax = sns.heatmap(arr)
  </code></pre>
  
  <p>Usually I would change the <code>labelsize</code> keyword using the <code>tick_params</code> method on a colorbar axes object, but with the <code>heatmap()</code> function I can only pass kwargs to the colorbar constructor. How can I modify the tick label size for the colorbar in this plot?</p>