Update app.py for slider to only have int values so range doesn't fail

I tried this demo on Gradio Docs and the run failed for me, when I tweaked slider value.

Cause was default increment allows float values and `range(steps)` fails for float values. Thus solving it in Gradio's idiomatic way... adding `step=1` to *Slider* would only allow steps:int to be used. Avoiding error scenarios.

app.py

@@ -13,7 +13,7 @@ def fake_diffusion(steps):
     yield image
 
 demo = gr.Interface(fake_diffusion, 
-                    inputs=gr.Slider(1, 10, 3), 
+                    inputs=gr.Slider(1, 10, 3, step=1), 
                     outputs="image")
 
 # define queue - required for generators