[evince] flatpak: Bump poppler's version

[Germán Poo-Caamaño <gpoo src gnome org>]

commit 26e05c06bd9cf5d7086be4a5c4db3787d5d207be
Author: Germán Poo-Caamaño <gpoo gnome org>
Date:   Thu Oct 11 12:09:11 2018 -0300

    flatpak: Bump poppler's version

 build-aux/flatpak/org.gnome.Evince.json | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/build-aux/flatpak/org.gnome.Evince.json b/build-aux/flatpak/org.gnome.Evince.json
index 20af54a0..91eb4b7e 100644
--- a/build-aux/flatpak/org.gnome.Evince.json
+++ b/build-aux/flatpak/org.gnome.Evince.json
@@ -124,8 +124,8 @@
             "sources": [
                 {
                     "type": "archive",
-                    "url": "https://poppler.freedesktop.org/poppler-0.66.0.tar.xz";,
-                    "sha256": "2c096431adfb74bc2f53be466889b7646e1b599f28fa036094f3f7235cc9eae7"
+                    "url": "https://poppler.freedesktop.org/poppler-0.68.0.tar.xz";,
+                    "sha256": "f90d04f0fb8df6923ecb0f106ae866cf9f8761bb537ddac64dfb5322763d0e58"
                 }
             ]
         },