postgresql-unaccent: remove port

[dgilman]

Description

This port isn't used in MacPorts anymore. In the wider world it seems to only be used by the Musicbrainz server. Its standalone repo (the homepage in the Portfile) now points users to the library included in the main Musicbrainz server repo. And it now seems that not even the Musicbrainz server is using a standalone unaccent anymore, they're using the unaccent package that's shipped as part of PostgreSQL itself as of 2020. metabrainz/musicbrainz-server@e48c61c

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 14.6.1 23G93 x86_64
Command Line Tools 15.3.0.0.1.1708646388

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL in commit message?
• checked your Portfile with port lint --nitpick?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?
• checked that the Portfile's most important variants haven't been broken?