[gnome-mines] Use gnome games stable version for flatpak.

[Robert Roth <robertroth src gnome org>]

commit b3136bf1520ffa5f8604e06342cd8292f4697b5c
Author: Robert Roth <robert roth off gmail com>
Date:   Sat Mar 12 18:02:23 2022 +0000

    Use gnome games stable version for flatpak.

 build-aux/org.gnome.Mines.json | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/build-aux/org.gnome.Mines.json b/build-aux/org.gnome.Mines.json
index d557f0e..d025fc7 100644
--- a/build-aux/org.gnome.Mines.json
+++ b/build-aux/org.gnome.Mines.json
@@ -39,6 +39,7 @@
                     "buildsystem": "meson",
                     "sources": [{
                         "type": "git",
+                        "branch": "games-1-8",
                         "url": "https://gitlab.gnome.org/GNOME/libgnome-games-support.git";
                     }]
                 }