Update absolutely gem version requirement

Author: jgarber623

link-header-parser.gemspec

@@ -22,5 +22,5 @@ Gem::Specification.new do |spec|
   spec.metadata['bug_tracker_uri'] = "#{spec.homepage}/issues"
   spec.metadata['changelog_uri']   = "#{spec.homepage}/blob/v#{spec.version}/CHANGELOG.md"
 
-  spec.add_runtime_dependency 'absolutely', '~> 5.0'
+  spec.add_runtime_dependency 'absolutely', '~> 5.1'
 end