Fixed "out_indices" and "out_features" in config

These fields were previously being stored incorrectly as "_out_features" and "_out_indices" with the underscore prefix. This was an error, and they should be stored without the prefix as "out_indices" and "out_features" for proper loading as a backbone model.

config.json

@@ -1,11 +1,11 @@
 {
   "_name_or_path": "FoamoftheSea/pvt_v2_b1",
-  "_out_features": [
+  "out_features": [
     "stage2",
     "stage3",
     "stage4"
   ],
-  "_out_indices": [
+  "out_indices": [
     1,
     2,
     3