x11-fonts/libXfont2: update to 2.0.6

Changes: https://gitlab.freedesktop.org/xorg/lib/libxfont/-/compare/libXfont2-2.0.5...libXfont2-2.0.6
Reviewed by: diizzy, jbeich
Tested by: arrowd
Pull Request: https://github.com/freebsd/freebsd-ports/pull/273
Sponsored by: Serenity Cybersecurity, LLC