software-properties uses deprecated apt-key

software-properties still references apt-key, which is deprecated upstream (https://blog.jak-linux.org/2021/06/20/migrating-away-apt-key/):

$ grep -r apt-key
tests/test_dbus.py: # test apt-key update
tests/test_aptauth.py: "/usr/bin/apt-key",
tests/test_aptauth.py: stderr="Warning: apt-key is deprecated.\n",
debian/changelog: - thus, add-apt-key for PPAs observes https_proxy for key retrieval
debian/changelog: - stop using apt-key for installing keys
debian/changelog: * Port AptAuth.py from gpg command parsing to apt-key command
debian/changelog: - fix incorrect call call to apt-key for the fingerprint, thanks
softwareproperties/SoftwareProperties.py: # apt-key stuff
softwareproperties/SoftwareProperties.py: """ Run apt-key update """
softwareproperties/AptAuth.py: cmd = ["/usr/bin/apt-key", "--quiet", "adv", "--with-colons", "--batch", "--fixed-list-mode", "--list-keys"]
softwareproperties/AptAuth.py: cmd = ["/usr/bin/apt-key", "--quiet", "--fakeroot", "add", filename]
softwareproperties/AptAuth.py: cmd = ["/usr/bin/apt-key", "--quiet", "--fakeroot", "update"]
softwareproperties/AptAuth.py: cmd = ["/usr/bin/apt-key", "--quiet", "--fakeroot", "rm", key]
$

apt-key will eventually go away, and software-properties needs to adapt.