PYTHON-2721 Reenable regex flags test on MongoDB 5.0+ (#779)

Author: juliusgeo

test/test_collection.py

@@ -1132,7 +1132,6 @@ def test_fields_specifier_as_dict(self):
         self.assertTrue("x" not in db.test.find_one(projection={"x": 0}))
         self.assertTrue("mike" in db.test.find_one(projection={"x": 0}))
 
-    @client_context.require_version_max(4, 9, -1)  # PYTHON-2721
     def test_find_w_regex(self):
         db = self.db
         db.test.delete_many({})