[3.11] gh-108915: Removes extra backslashes in str.split docstring (GH-109044) (#109062)

[3.11] gh-108915: Removes extra backslashes in str.split docstring (GH-109044).
(cherry picked from commit e7d5433f944a5725aa82595f9251abfc8a63d333)

Co-authored-by: Daniel Weiss <134341009+justdan6@users.noreply.github.com>