[eog] flatpak: Build Exempi from the stable branch

[Felix Riemann <friemann src gnome org>]

commit 2fa11258e8ed163baeb3ef7de79b26c508c12476
Author: Felix Riemann <friemann gnome org>
Date:   Mon Jul 13 20:35:22 2020 +0200

    flatpak: Build Exempi from the stable branch
    
    While master is still at release 2.5.0 the stable exempi-2.5-branch
    contains already release 2.5.2.

 org.gnome.Eog.json | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/org.gnome.Eog.json b/org.gnome.Eog.json
index b99c26fdd..c85c127a5 100644
--- a/org.gnome.Eog.json
+++ b/org.gnome.Eog.json
@@ -92,7 +92,8 @@
             "sources" : [
                 {
                     "type" : "git",
-                    "url" : "https://anongit.freedesktop.org/git/exempi.git";
+                    "url" : "https://gitlab.freedesktop.org/libopenraw/exempi.git";,
+                    "branch" : "exempi-2.5-branch"
                 }
             ]
         },