ruff: Fix UP035 Import from collections.abc, typing instead.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/tests/test_signup.py

@@ -1,7 +1,8 @@
 import re
 import time
+from collections.abc import Sequence
 from datetime import timedelta
-from typing import TYPE_CHECKING, Any, Sequence, Union
+from typing import TYPE_CHECKING, Any, Union
 from unittest.mock import MagicMock, patch
 from urllib.parse import quote, quote_plus, urlencode, urlsplit