Update preprocessor_config.json

preprocessor_config.json

@@ -25,15 +25,15 @@
   "do_resize": false,
   "do_thumbnail": true,
   "image_mean": [
-    0.5,
-    0.5,
-    0.5
+    0.485,
+    0.456,
+    0.406
   ],
   "image_processor_type": "DonutImageProcessor",
   "image_std": [
-    0.5,
-    0.5,
-    0.5
+    0.229,
+    0.224,
+    0.225
   ],
   "processor_class": "DonutProcessor",
   "resample": 2,