Set output image format to PNG for higher quality

By default, Gradio `Image` and `Gallery` serve the output image recompressed to a terrible-quality WebP; setting the format explicitly to a lossless format avoids that behavior.

app.py

@@ -428,7 +428,8 @@ with gr.Blocks(css=css) as WeShop:
                         type="pil",
                         label="Result",
                         elem_classes=["image-container", "hide-buttons"],
-                        interactive=False
+                        interactive=False,
+                        format="png",
                     )
             with gr.Row():
                 submit_button = gr.Button("Generate")