[gnome-builder] flatpak: update download url

[Christian Hergert <chergert src gnome org>]

commit b0f744ae7e666704cd667ca2c76f7043502947a6
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jun 25 20:44:40 2018 -0700

    flatpak: update download url
    
    we get forbidden, lets see if this redirect helps.

 build-aux/flatpak/org.gnome.Builder.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/build-aux/flatpak/org.gnome.Builder.json b/build-aux/flatpak/org.gnome.Builder.json
index f81497b08..56822648a 100644
--- a/build-aux/flatpak/org.gnome.Builder.json
+++ b/build-aux/flatpak/org.gnome.Builder.json
@@ -148,7 +148,7 @@
             "sources" : [
                 {
                     "type" : "archive",
-                    "url" : "http://prdownloads.sourceforge.net/ctags/ctags-5.8.tar.gz";,
+                    "url" : "http://downloads.sourceforge.net/project/ctags/ctags/5.8/ctags-5.8.tar.gz";,
                     "sha256" : "0e44b45dcabe969e0bbbb11e30c246f81abe5d32012db37395eb57d66e9e99c7"
                 }
             ]