Add stubs package for lxml. (#15697)

The stubs have some issues so this has some generous cast
and ignores in it, but it is better than not having stubs.

Note that confusing that Element is a function which creates
_Element instances (and similarly for Comment).

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/media/test_oembed.py b/tests/media/test_oembed.py

index c8bf8421da..3bc19cb1cc 100644
--- a/tests/media/test_oembed.py
+++ b/tests/media/test_oembed.py
@@ -28,7 +28,7 @@ from tests.unittest import HomeserverTestCase
 try:
     import lxml
 except ImportError:
-    lxml = None
+    lxml = None  # type: ignore[assignment]
 
 
 class OEmbedTests(HomeserverTestCase):