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, 0 deletions

diff --git a/pyproject.toml b/pyproject.toml
index 7227bc7523..4476f57ca7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -314,6 +314,7 @@ black = ">=22.3.0"
 ruff = "0.0.265"
 
 # Typechecking
+lxml-stubs = ">=0.4.0"
 mypy = "*"
 mypy-zope = "*"
 types-bleach = ">=4.1.0"