fix: python 3.10 compatibility

Author: ziirish

flask_restx/reqparse.py

@@ -1,6 +1,9 @@
 import decimal
 
-from collections import Hashable
+try:
+    from collections.abc import Hashable
+except ImportError:
+    from collections import Hashable
 from copy import deepcopy
 from flask import current_app, request