Add "safe_serialization": true as is required for custom Nomic models

sentence_bert_config.json

@@ -2,6 +2,7 @@
   "max_seq_length": 8192,
   "do_lower_case": false,
   "model_args": {
-    "add_pooling_layer": false
+    "add_pooling_layer": false,
+    "safe_serialization": true
   }
 }