add toml support for py39 through pip

Author: blagasz

tests/test_number_spelling.py

@@ -1,7 +1,11 @@
 import unittest
 
 import pytest
-import tomllib
+
+try:
+    import tomllib
+except ModuleNotFoundError:
+    import pip._vendor.tomli as tomllib
 
 from babel import numbers, rbnf
 from babel.localedata import locale_identifiers