systemd-nspawn: relax PrivateUsers check

this options allows two colon-separated number as value, for instances which
is quite difficult to check.

Changed files
-1
nixos
modules
system
-1
nixos/modules/system/boot/systemd-nspawn.nix
···
])
(assertValueOneOf "Boot" boolValues)
(assertValueOneOf "ProcessTwo" boolValues)
-
(assertValueOneOf "PrivateUsers" (boolValues ++ [ "pick" ]))
(assertValueOneOf "NotifyReady" boolValues)
];