Remove duplicate ostruct entry from Gemfile

[larouxn]

It appears #2202 added a second ostruct entry to the Gemfile which leads to the following warning. We should remove it as we only need the single pre-existing entry.

See lines 28 and 42. 👇

rouge/Gemfile

Lines 19 to 44 in 474be87

	group :development do
	gem 'pry'
	# Needed for a Rake task
	gem 'git'
	gem 'yard'
	gem 'rubocop', '~> 1.0', '<= 1.11'
	gem 'rubocop-performance'
	gem 'ostruct'
	# docs
	gem 'github-markup'
	# for visual tests
	gem 'sinatra'
	gem 'puma'
	gem 'shotgun'
	gem "mutex_m" if RUBY_VERSION >= '3.4'
	gem "base64" if RUBY_VERSION >= '3.4'
	gem 'ostruct'
	gem 'reline'
	end

[tancnle]

Thanks for fixing this @larouxn 🚀