Update app.py

app.py

@@ -1,7 +1,7 @@
 import matplotlib
 matplotlib.use('agg')
 import os
-os.system('Xvfb :1 -screen 0 1600x1200x32  &')    # create virtual display with size 1600x1200 and 16 bit color. Color can be changed to 24 or 8
+os.system('Xvfb :1 -screen 0 1600x1200x24  &')    # create virtual display with size 1600x1200 and 16 bit color. Color can be changed to 24 or 8
 os.environ['DISPLAY']=':1.0'    # tell X clients to use our virtual DISPLAY :1.0
 
 from PIL import Image