Use type hinting generics in standard collections (#19046)

aka PEP 585, added in Python 3.9

 - https://peps.python.org/pep-0585/
 - https://docs.astral.sh/ruff/rules/non-pep585-annotation/

tests/storage/test_rollback_worker.py

@@ -18,7 +18,6 @@
 # [This file includes modifications made by New Vector Limited]
 #
 #
-from typing import List
 from unittest import mock
 
 from twisted.internet.testing import MemoryReactor
@@ -34,7 +33,7 @@ from synapse.util.clock import Clock
 from tests.unittest import HomeserverTestCase
 
 
-def fake_listdir(filepath: str) -> List[str]:
+def fake_listdir(filepath: str) -> list[str]:
     """
     A fake implementation of os.listdir which we can use to mock out the filesystem.