fix rubocop warnings

lib/github_changelog_generator/fetcher.rb

@@ -26,12 +26,12 @@ module GitHubChangelogGenerator
       @project = @options[:project]
       @github_token = fetch_github_token
       @tag_times_hash = {}
-      github_options = {per_page: PER_PAGE_NUMBER}
+      github_options = { per_page: PER_PAGE_NUMBER }
       github_options[:oauth_token] = @github_token unless @github_token.nil?
       github_options[:endpoint] = options[:github_endpoint] unless options[:github_endpoint].nil?
       github_options[:site] = options[:github_endpoint] unless options[:github_site].nil?
 
-      @github = check_github_response{Github.new github_options}
+      @github = check_github_response { Github.new github_options }
     end
 
     # Returns GitHub token. First try to use variable, provided by --token option,