archivers/gcab: update to 1.6

Changelog:
 New Features:
  - Allow specifying the allowed compression formats at runtime (!15)
    This would allow us, for example, to disable the slightly scary LZX
    compression format when parsing unknown files.
 Bugfixes:
  - Do not require git when building from a tarball
https://gitlab.gnome.org/GNOME/gcab/-/blob/v1.6/NEWS

While here pet portclippy.

PR:		279024
Approved by:	gnome (maintainer, timeout 2 weeks)