[gnome-photos] flatpak: Update exiv2 to 0.26

[Debarshi Ray <debarshir src gnome org>]

commit b8a090c64f932dfa4558266935acf5852a5bd712
Author: Debarshi Ray <debarshir gnome org>
Date:   Tue Oct 3 16:58:28 2017 +0200

    flatpak: Update exiv2 to 0.26

 flatpak/org.gnome.Photos.json |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/flatpak/org.gnome.Photos.json b/flatpak/org.gnome.Photos.json
index 84dfb6e..a7ee77c 100644
--- a/flatpak/org.gnome.Photos.json
+++ b/flatpak/org.gnome.Photos.json
@@ -170,8 +170,8 @@
             "sources": [
                 {
                     "type": "archive",
-                    "url": "http://www.exiv2.org/exiv2-0.25.tar.gz";,
-                    "sha256": "c80bfc778a15fdb06f71265db2c3d49d8493c382e516cb99b8c9f9cbde36efa4"
+                    "url": "http://exiv2.org/builds/exiv2-0.26-trunk.tar.gz";,
+                    "sha256": "c75e3c4a0811bf700d92c82319373b7a825a2331c12b8b37d41eb58e4f18eafb"
                 },
                 {
                     "type": "patch",