title: How to label animation frame in plotly express?
body: <p>I am using plotly express in python</p>
  <p>I have a px.choropleth figure with a slider using animation_frame</p>
  <p>The label for animation frame is currently animation_frame=</p>
  <p>I would like to change it to 'Year'</p>
  <p>How can I change the label of the animation_frame?</p>