dunstify does not build with libnotify >=0.8.4

[ajacoutot]

Hi.

Since libnotify 0.8.4, the priv pointer in NotifyNotification is not exposed externally anymore.
See https://gitlab.gnome.org/GNOME/libnotify/-/commit/f413d8109cd2203dee08da3ec116bf8adc81e6ca

dunstify.c:205:23: error: no member named 'priv' in 'struct _NotifyNotification'
    knickers *kn = n->priv;
                   ~  ^
dunstify.c:213:23: error: no member named 'priv' in 'struct _NotifyNotification'
    knickers *kn = n->priv;
                   ~  ^

[bynect]

thanks for the heads up

[bynect]

fixed by #1444