audio/praat: update version and fix run-depends

The update of Charis fonts to 7.0 changed the package name,
leading to run-depends fallout. Chase that; no PORTREVISION
bump needed because I may as well update to the latest version.

Release notes (as always) at
https://www.fon.hum.uva.nl/praat/manual/What_s_new_.html

Many new trigraphs, better scripting, and Charis 7 font support.