[gnome-tweaks] appearance: Add Sound translatable string as placeholder

[Jeremy Bicha <jbicha src gnome org>]

commit 7648509ae3b0c4c720069955bfe11f174ef8f6a0
Author: Jeremy Bicha <jbicha ubuntu com>
Date:   Wed Aug 1 10:44:16 2018 -0400

    appearance: Add Sound translatable string as placeholder
    
    We may add a Sound theme dropdown box to the Appearance panel for 3.30.
    
    https://gitlab.gnome.org/GNOME/gnome-tweaks/merge_requests/7
    
    This restores the "Sound" translatable string dropped earlier this week
    in commit 02c7c0ac. We're adding the string now so that adding the new
    dropdown box later won't require extra work from translators then.

 gtweak/tweaks/tweak_group_appearance.py | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/gtweak/tweaks/tweak_group_appearance.py b/gtweak/tweaks/tweak_group_appearance.py
index fff578c..ff0b98b 100644
--- a/gtweak/tweaks/tweak_group_appearance.py
+++ b/gtweak/tweaks/tweak_group_appearance.py
@@ -23,6 +23,11 @@ from gtweak.widgets import ListBoxTweakGroup, GSettingsSwitchTweak, GSettingsCom
 _shell = GnomeShellFactory().get_shell()
 _shell_loaded = _shell is not None
 
+# This is a placeholder for a Sound Theme dropdown box for the Appearance panel.
+# This will allow us to add the dropdown box later without needing a new
+# translatable string.
+sound_label = _("Sound")
+
 class GtkThemeSwitcher(GSettingsComboTweak):
     def __init__(self, **options):
         GSettingsComboTweak.__init__(self,