[gnome-flashback] rename libgnome-volume-control submodule

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 9fb514c7955f99858cee1e3655cc530f9bee6751
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Jun 28 13:27:02 2020 +0300

    rename libgnome-volume-control submodule

 .gitmodules | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitmodules b/.gitmodules
index d31f626..d1e1900 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,4 +1,4 @@
-[submodule "gnome-flashback/libsound-applet/gvc"]
+[submodule "libgnome-volume-control"]
        path = gvc/gvc
        url = https://gitlab.gnome.org/GNOME/libgnome-volume-control.git
        ignore = untracked