Update app.py

app.py

@@ -8,7 +8,7 @@ os.system('apt-get update; apt-get install optipng')
 os.system('wget https://github.com/JingyunLiang/SwinIR/releases/download/v0.0/003_realSR_BSRGAN_DFO_s64w8_SwinIR-M_x4_GAN.pth -P experiments/pretrained_models')
 
 def inference(img):
-    os.system('mkdir test')
+    os.system('mkdir -p test')
     img.save("test/1.png", "PNG")
     os.system('python main_test_swinir.py --task real_sr --model_path experiments/pretrained_models/003_realSR_BSRGAN_DFO_s64w8_SwinIR-M_x4_GAN.pth --folder_lq test --scale 4')
     os.system("optipng -o5 results/swinir_real_sr_x4/1_SwinIR.png")