build(release): bump version to 0.3.1

Author: tuzumkuru

init.rb

@@ -2,7 +2,7 @@
   name 'Redmine AI Summary Plugin'
   author 'Tolga Uzun'
   description 'A plugin for generating AI summaries on issues.'
-  version '0.3.0'
+  version '0.3.1'
   url 'https://github.com/tuzumkuru/redmine_ai_summary'
   author_url 'https://github.com/tuzumkuru'
   requires_redmine :version_or_higher => '5.0.0'