Use NULL for nick/blurb in GObject params

As they are only used by gstreamer for gst-inspect & other tools.
Projects like Mutter/gtk have completely dropped them as well, so follow
their path

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3505>

js/ui/calendar.js

@@ -95,11 +95,11 @@ export const EventSourceBase = GObject.registerClass({
     GTypeFlags: GObject.TypeFlags.ABSTRACT,
     Properties: {
         'has-calendars': GObject.ParamSpec.boolean(
-            'has-calendars', 'has-calendars', 'has-calendars',
+            'has-calendars', null, null,
             GObject.ParamFlags.READABLE,
             false),
         'is-loading': GObject.ParamSpec.boolean(
-            'is-loading', 'is-loading', 'is-loading',
+            'is-loading', null, null,
             GObject.ParamFlags.READABLE,
             false),
     },