This makes the profile readable by older Guix instances. This is a
followup to c9fbd40785a99e13a59d8e530830ce85220a9871.
Fixes <https://issues.guix.gnu.org/57306>.
Reported by Arun Isaac <arunisaac@systemreboot.net>.
* guix/profiles.scm (%manifest-format-version): Export.
* guix/scripts/package.scm (build-and-use-profile): Add #:format-version
and pass it to 'profile-derivation'.
* guix/scripts/pull.scm (build-and-install): Pass #:format-version 3.
67a6828b2b