Update changelog URL

Author: Mattia Roccoberton

activeadmin_blaze_theme.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |spec|
 
   spec.metadata['homepage_uri'] = spec.homepage
   spec.metadata['source_code_uri'] = spec.homepage
-  spec.metadata['changelog_uri'] = 'https://raw.githubusercontent.com/blocknotes/activeadmin_blaze_theme/master/CHANGELOG.md'
+  spec.metadata['changelog_uri'] = 'https://github.com/blocknotes/activeadmin_blaze_theme/blob/master/CHANGELOG.md'
   spec.metadata['rubygems_mfa_required'] = 'true'
 
   spec.files         = Dir["{app,lib}/**/*", 'LICENSE.txt', 'README.md', 'index.js', 'package.json']