cleanup: Use null for nick/blurb in ParamSpecs

As they are only used by gstreamer for gst-inspect & other tools.
Projects like mutter and gtk have already completely dropped them,
so follow their lead.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell-extensions/-/merge_requests/347>
(cherry picked from commit 46a4fa0976)

extensions/window-list/extension.js

@@ -172,7 +172,7 @@ class BaseButton extends DashItemContainer {
             GTypeFlags: GObject.TypeFlags.ABSTRACT,
             Properties: {
                 'ignore-workspace': GObject.ParamSpec.boolean(
-                    'ignore-workspace', 'ignore-workspace', 'ignore-workspace',
+                    'ignore-workspace', null, null,
                     GObject.ParamFlags.READWRITE,
                     false),
             },