tigervnc: Update to 1.12.0

[eborisch]

Description

Updating to latest. Works for me on BigSur (11.6.3).

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 11.6.3 20G415 x86_64
Xcode 13.1 13A1030d

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?
• 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?

[macportsbot]

Notifying maintainers:
@ryandesign for port tigervnc.

[eborisch]

See also: https://trac.macports.org/ticket/54851