Revert temporary fix for Octokit

Reverting 3d4196a now that the issue
has been fixed upstream. See https://github.com/octokit/octokit.rb/releases/tag/v4.24.0

Author: waiting-for-dev

lib/solidus_dev_support/rake_tasks.rb

@@ -78,7 +78,6 @@ def install_changelog_task
 
       GitHubChangelogGenerator::RakeTask.new(:changelog) do |config|
         require 'octokit'
-        require 'octokit/repository'
         repo = Octokit::Repository.from_url(gemspec.metadata['source_code_uri'] || gemspec.homepage)
 
         config.user = repo.owner