Try to give access to notifications

It'd be better to fix WebKit to use the notifications portal instead,
but got to start somewhere.

org.gnome.Epiphany.yaml

@@ -19,6 +19,7 @@ finish-args:
   - --talk-name=ca.desrt.dconf
   - --env=DCONF_USER_CONFIG_DIR=.config/dconf
   - --talk-name=org.freedesktop.secrets
+  - --talk-name=org.freedesktop.Notifications
   - --filesystem=xdg-download
 build-options:
   cflags: -O2 -g