[discourse-web] Discourse now requires ruby >= 2.6

[Andrea Veri <averi src gnome org>]

commit 27798fde725368b9bf9814015211f1ff35b0d937
Author: Andrea Veri <av gnome org>
Date:   Mon Oct 14 17:38:00 2019 +0000

    Discourse now requires ruby >= 2.6

 Dockerfile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/Dockerfile b/Dockerfile
index da465c6..004ccdd 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:2.5.3
+FROM ruby:2.6.5
 LABEL maintainer="GNOME Sysadmins <gnome-sysadmin gnome org>"
 
 ### Install prerequisites #############################