pkgdb-proxy: include the epel8 release in the list of active releases

This way mdapi will pick it up and start offering the epel8 repo info
via its API.

Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>

roles/pkgdb-proxy/files/pkgdb-gnome-software-collections.json

@@ -363,6 +363,17 @@
       "status": "Active",
       "version": "7"
     },
+    {
+      "allow_retire": true,
+      "branchname": "epel8",
+      "date_created": "2019-08-12 4:55:15",
+      "date_updated": "2019-08-12 4:55:15",
+      "dist_tag": ".el8",
+      "koji_name": "epel8",
+      "name": "Fedora EPEL",
+      "status": "Active",
+      "version": "8"
+    },
     {
       "allow_retire": true,
       "branchname": "el6",