Update config.json

Fix config for backward compatibility with [#17785](https://github.com/huggingface/transformers/commit/abc400b06a8ab26cd438b6e9add3aad082ffc48f)

config.json

@@ -24,5 +24,6 @@
   "transformers_version": "4.19.2",
   "use_cache": false,
   "vocab_size": 50265,
-  "word_embed_proj_dim": 2560
-}
+  "word_embed_proj_dim": 2560,
+  "_remove_final_layer_norm": true
+}