bug#62442: Latest Guix binary download permission issues

[Lars-Dominik Braun]

Hi,

as noted in [1] the latest Guix binary (tar.xz) from CI has the following
directory entry:

    drwx------ root/root         0 1970-01-01 01:00 ./

When installing this tarball using guix-install.sh the system will
be bricked instantly, because the `tar -xf` command does not include
--no-overwrite-dir, causing / to become readable only for the root user.

Cheers,
Lars

[1] https://github.com/PromyLOPh/guix-install-action/issues/20