[polari] roomList: Use PopoverMenu for context menu

[Marge Bot <marge-bot src gnome org>]

commit b3e2f124b3522b22afd560b8c466dc94890cd337
Author: Florian Müllner <fmuellner gnome org>
Date:   Sat Oct 10 04:39:53 2020 +0200

    roomList: Use PopoverMenu for context menu
    
    In GTK4, the ability to populate a popover from a menu model moved
    to PopoverMenu.
    
    Part-of: <https://gitlab.gnome.org/GNOME/polari/-/merge_requests/228>

 src/roomList.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/roomList.js b/src/roomList.js
index 0b45ea27..7c48ec08 100644
--- a/src/roomList.js
+++ b/src/roomList.js
@@ -229,7 +229,7 @@ const RoomRow = GObject.registerClass({
 });
 
 const RoomRowPopover = GObject.registerClass(
-class RoomRowPopover extends Gtk.Popover {
+class RoomRowPopover extends Gtk.PopoverMenu {
     _init(row) {
         super._init({
             position: Gtk.PositionType.BOTTOM,
@@ -254,7 +254,7 @@ class RoomRowPopover extends Gtk.Popover {
         const label = isRoom ?  _('Leave chatroom') : _('End conversation');
         this._menu.append(label, `app.leave-room(("${this._row.room.id}", ""))`);
 
-        this.bind_model(this._menu, null);
+        this.set_menu_model(this._menu);
     }
 
     vfunc_map() {