pdb docs: workaround for double semicolon in strings (GH-17011)

see https://github.com/gotcha/ipdb/issues/172



Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
(cherry picked from commit 2888b110)

Co-authored-by: Godefroid Chapelle <gotcha@bubblenet.be>