Add fallback for ujson import (python-lsp#541)

Co-authored-by: Савеленко Алексей Николаевич <a.savelenko@tinkoff.ru>

Author: Savalek

pylsp/python_lsp.py

@@ -9,7 +9,11 @@
 from functools import partial
 from typing import Any, Dict, List
 
-import ujson as json
+try:
+    import ujson as json
+except Exception:
+    import json
+
 from pylsp_jsonrpc.dispatchers import MethodDispatcher
 from pylsp_jsonrpc.endpoint import Endpoint
 from pylsp_jsonrpc.streams import JsonRpcStreamReader, JsonRpcStreamWriter