[gnome-control-center/wip/hadess/update-libgvc-3.38] subprojects: Update libgvc

[Bastien Nocera <hadess src gnome org>]

commit 68bb33846268145061abcf54b50fcbea021d7528
Author: Bastien Nocera <hadess hadess net>
Date:   Mon Sep 21 11:08:16 2020 +0200

    subprojects: Update libgvc
    
    This update is necessary to add support for recent UCM related changes
    in ALSA and PulseAudio.
    
    See https://gitlab.gnome.org/GNOME/libgnome-volume-control/-/merge_requests/10

 subprojects/gvc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/subprojects/gvc b/subprojects/gvc
index 468022b70..7a621180b 160000
--- a/subprojects/gvc
+++ b/subprojects/gvc
@@ -1 +1 @@
-Subproject commit 468022b708fc1a56154f3b0cc5af3b938fb3e9fb
+Subproject commit 7a621180b46421e356b33972e3446775a504139c