Testing device-level configs

See https://github.com/huggingface/transformers.js/pull/1276

config.json

@@ -1,6 +1,16 @@
 {
   "model_type": "modnet",
   "transformers.js_config": {
-    "dtype": "fp32"
+    "dtype": "fp32",
+    "device_config": {
+      "webnn": {
+        "free_dimension_overrides": {
+          "batch_size": 1,
+          "num_channels": 3,
+          "height": 256,
+          "width": 256
+        }
+      }
+    }
   }
 }