tests: Fix distcheck breaking on gpg dir not writable
tests: Fix distcheck breaking on gpg dir not writable

We make a copy of the gpg homedir so that gpg can write (e.g. a lock file)
to the directory.

amigadave/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,amigadave/flatpak,GeorgesStavracas/flatpak,handsome-feng/flatpak,alexlarsson/xdg-app,flatpak/flatpak,GeorgesStavracas/flatpak,GeorgesStavracas/flatpak,handsome-feng/flatpak,handsome-feng/flatpak,alexlarsson/xdg-app,amigadave/flatpak,GeorgesStavracas/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,flatpak/flatpak,alexlarsson/xdg-app,flatpak/flatpak,alexlarsson/xdg-app,amigadave/flatpak,flatpak/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak,GeorgesStavracas/flatpak