title: xgb.plot_tree font size python
body: <p>I make a picture as bellow</p>
  
  <pre><code>import matplotlib.pylab as plt
  %matplotlib inline
  from matplotlib.pylab import rcParams
  </code></pre>
  
  <p>..... i miss code for xgboost</p>
  
  <pre><code>xgb.plot_tree(clf, num_trees=2)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/KDMHp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KDMHp.png" alt="enter image description here"></a></p>
  
  <p>And i want to increase font size </p>
  
  <pre><code>font = {'size'   : 22}
  plt.rc('font', **font)
  </code></pre>
  
  <p>or</p>
  
  <pre><code>plt.rcParams.update({'font.size': 32})
  </code></pre>
  
  <p>but font size is the same
  how to change font size in xgb.plot_tree?</p>