scripts: misc: guix.sh: fix typo.

After installing Guix with the following command on PureOS 10
(byzantium) with the following command:
    $ sudo pkcon -y --allow-reinstall install guix
we have:
    $ ./resources/dependencies/guix
    ./resources/dependencies/guix: 91: .:
    cannot open [$HOME]/.config/guix/current/etc/profile: No such file

This should fix it.

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
Acked-by: Adrien 'neox' Bourmault <neox@gnu.org>

resources/scripts/misc/guix.sh

@@ -86,7 +86,7 @@ guix_latest_release="1.4.0"
 
 source_guix_profile()
 {
-    if [ "${HOME}"/.config/guix/current/etc/profile ] ; then
+    if [ -f "${HOME}"/.config/guix/current/etc/profile ] ; then
 	GUIX_PROFILE="${HOME}/.config/guix/current"
 	. "$GUIX_PROFILE"/etc/profile
     fi