After 04 Oct 2026 (Python 3.10 end of life), we should start using `typing.Self` to annotate function input types (ie undo https://github.com/FEniCS/ufl/commit/86a2140aa0ea3c65e5d96de1ad8f2bfc06347a60).
After 04 Oct 2026 (Python 3.10 end of life), we should start using
typing.Selfto annotate function input types (ie undo 86a2140).