devel/py-prettyprinter: Update to 0.18.0

Changes: https://github.com/tommikaikkonen/prettyprinter/commit/53ba5f934f24228315ef10898fc2b73370349696

PR: 255274
Reported by: Gian-Simon Purkert <gspurki AT gmail DOT com>
Approved by: Patrice Clement <monsieurp AT gentoo DOT org> (maintainer)