GroupchatJoin: Set default size

gajim/gtk/groupchat_join.py

@@ -47,6 +47,7 @@ def __init__(self, account: str, jid: str) -> None:
         self.set_show_menubar(False)
         self.set_title(_('Join Group Chat'))
         self.set_type_hint(Gdk.WindowTypeHint.DIALOG)
+        self.set_default_size(500, 550)
 
         self._destroyed = False
         self.account = account