Update config.json

config.json

@@ -1,10 +1,12 @@
 {
   "model_type": "modnet",
   "transformers.js_config": {
-    "free_dimension_overrides": {
-      "batch_size": 1,
-      "height": 256,
-      "width": 320
+    "webnn": {
+      "free_dimension_overrides": {
+        "batch_size": 1,
+        "height": 256,
+        "width": 320
+      }
     }
   }
 }