title: How to make plotly axes display only integer numbers
body: <p>I have a plotly barplot in a shiny app, showing factor levels on X axis. But on some number of inputs (2,3,4) it shows marks like 1.5, 2.5 etc (see an image). So there is a question: can I somehow make the X axis marks show only integer values?</p>
  
  <p><a href="https://i.stack.imgur.com/SAKPL.png" rel="noreferrer"><img src="https://i.stack.imgur.com/SAKPL.png" alt="sample"></a></p>