[gnome-shell/wip/hadess/update-libgvc] subprojects: Update libgvc

[Bastien Nocera <hadess src gnome org>]

commit eccb18f81470c72e46b9d74a54716748f0ec3d54
Author: Bastien Nocera <hadess hadess net>
Date:   Mon Sep 21 11:06:56 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 ec5cf3e0de..7a621180b4 160000
--- a/subprojects/gvc
+++ b/subprojects/gvc
@@ -1 +1 @@
-Subproject commit ec5cf3e0de6715803e64b65abb059e2155b3d6de
+Subproject commit 7a621180b46421e356b33972e3446775a504139c