title: Change text font size in Bokeh LabelSet
body: <p>I have some plots deployed as a layout using Bokeh Server. For now it is working fine. But when I include the <code>text_font_size</code> attribute in the label set, it does not work anymore.</p>
  
  <pre><code>labels = LabelSet(x='datetime', y='bool_event', text='Code description', level='glyph',
                    x_offset=5, y_offset=5, source=ColumnDataSource(df2), render_mode='canvas',
                    text_font_size=10)
  </code></pre>
  
  <p>The error I get is the following:
  <a href="https://i.stack.imgur.com/MWyte.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MWyte.png" alt="Error"></a></p>
  
  <p>The actual layout is the following one:
  <a href="https://i.stack.imgur.com/AGIt3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/AGIt3.png" alt="Layout"></a></p>