Move flatpak manifest to top directory

.gitlab-ci.yml

-# SPDX-FileCopyrightText: 2018-2022 Bruce Cowan <bruce@bcowan.me.uk>
+# SPDX-FileCopyrightText: 2018-2023 Bruce Cowan <bruce@bcowan.me.uk>
 #
 # SPDX-License-Identifier: GPL-3.0-or-later
 flatpak:
   image: alpine:latest
   stage: build
   variables:
-    MANIFEST_PATH: "build-aux/uk.me.bcowan.Rugby.yml"
+    MANIFEST_PATH: "uk.me.bcowan.Rugby.yml"
     RUNTIME_REPO: "https://flathub.org/repo/flathub.flatpakrepo"
     FLATPAK_MODULE: "rugby"
     BUNDLE: "rugby.flatpak"