Fixes ruby 2.4 incompatibility

Author: dkastl

init.rb

@@ -9,7 +9,7 @@
   author 'Jens Krämer, Georepublic'
   author_url 'https://hub.georepublic.net/gtt/redmine_supply'
   description 'Add configurable supply items to issues'
-  version '1.2.0'
+  version '1.2.1'
 
   requires_redmine version_or_higher: '3.4.0'