www/pmwiki: update 2.2.80 -> 2.2.81
Changes:
- fixes an inconsistency with single line page text variables
- wikis enabling UTF-8 will be able to override the text direction when inserting right to left languages
- documentation update
PR: 204518
Submitted by: Torsten Zuhlsdorff <ports@toco-domains.de> (maintainer)