title: Matplotlib deprecation warning running through ubuntu application
body: <p>I'm running a program through shell on windows and keep getting this deprecation error. Here is the code being ran and the error message: </p>
  
  <p>Code:
  class Window:
      """
      Window to draw a gridworld instance using Matplotlib
      """</p>
  
  <pre><code>def __init__(self, title):
      self.fig = None
  
      self.imshow_obj = None
  
      # Create the figure and axes
      self.fig, self.ax = plt.subplots()
  
      # Show the env name in the window title
      self.fig.canvas.set_window_title(title)
  
      # Turn off x/y axis numbering/ticks
  
  
      self.ax.set_xticks([], [])
      self.ax.set_yticks([], [])
  
      # Flag indicating the window was closed
      self.closed = False
  
      def close_handler(evt):
          self.closed = True
  
      self.fig.canvas.mpl_connect('close_event', close_handler)
  
  def show_img(self, img):
  </code></pre>
  
  <p>Error: 
  /home/msaidi/gym-minigrid/gym_minigrid/window.py:31: MatplotlibDeprecationWarning: Passing the minor parameter of set_xticks() positionally is deprecated since Matplotlib 3.2; the parameter will become keyword-only two minor releases later.
    self.ax.set_xticks([], [])
  /home/msaidi/gym-minigrid/gym_minigrid/window.py:32: MatplotlibDeprecationWarning: Passing the minor parameter of set_yticks() positionally is deprecated since Matplotlib 3.2; the parameter will become keyword-only two minor releases later.
    self.ax.set_yticks([], [])</p>
  
  <p>When I compile the code in the ide I don't get any errors.</p>
  
  <p>I tried changing from self.ax.set_xticks to set_xticks and to ax.set_xticks and self.set_xticks and didn't work. </p>
  
  <p>Matplotlib version: 3.2.1
  python3
  running through (ubuntu windows application)</p>