devel/qt5-assistant: unbreak after 020693c166d1

Project MESSAGE: perl -w /usr/local/lib/qt5/bin/syncqt.pl -module QtHelp -version 5.15.8 -outdir /wrkdirs/usr/ports/devel/qt5-assistant/work/kde-qttools-5.15.8p1 -builddir /wrkdirs/usr/ports/devel/qt5-assistant/work/kde-qttools-5.15.8p1 /wrkdirs/usr/ports/devel/qt5-assistant/work/kde-qttools-5.15.8p1
sh: perl: not found

PR: 266007