Upgrade danger-changelog to ~> 0.8.0

Fixes undefined method 'github' in dry_run mode used by danger-pr-comment workflow.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dblock

Gemfile

@@ -22,7 +22,7 @@ end
 
 group :test do
   gem 'danger', '~> 9.5'
-  gem 'danger-changelog', '~> 0.7.0'
+  gem 'danger-changelog', '~> 0.8.0'
   gem 'danger-pr-comment', '~> 0.1.0'
   gem 'danger-toc', '~> 0.2.0'
   gem 'minitest'