[3.12] gh-146211: Reject CR/LF in HTTP tunnel request headers (GH-146212) (#148341)

gh-146211: Reject CR/LF in HTTP tunnel request headers (GH-146212)
(cherry picked from commit 05ed7ce7ae9e17c23a04085b2539fe6d6d3cef69)

Co-authored-by: Seth Larson <seth@python.org>
Co-authored-by: Illia Volochii <illia.volochii@gmail.com>