Remove some old dependencies.

Author: gkellogg

json-ld.gemspec

@@ -2,7 +2,6 @@
 # -*- encoding: utf-8 -*-
 
 is_java = RUBY_PLATFORM == 'java'
-ruby_version = RUBY_VERSION
 
 Gem::Specification.new do |gem|
   gem.version               = File.read('VERSION').chomp
@@ -28,14 +27,13 @@ Gem::Specification.new do |gem|
   gem.requirements          = []
   gem.add_runtime_dependency     'rdf',             '~> 3.1'
   gem.add_runtime_dependency     'multi_json',      '~> 1.14'
-  gem.add_runtime_dependency     'i18n',            '<= 1.5.1' if ruby_version < "2.3"
   gem.add_runtime_dependency     'link_header',     '~> 0.0', '>= 0.0.8'
   gem.add_runtime_dependency     'json-canonicalization', '~> 0.1'
   gem.add_runtime_dependency     'htmlentities',     '~> 4.3'
   gem.add_runtime_dependency     'rack',            '>= 1.6', '< 3.0'
   gem.add_development_dependency 'sinatra-linkeddata','~> 3.0'
   gem.add_development_dependency 'jsonlint',        '~> 0.3'  unless is_java
-  gem.add_development_dependency 'oj',              '~> 3.9'  unless is_java || ruby_version < "2.3"
+  gem.add_development_dependency 'oj',              '~> 3.9'  unless is_java
   gem.add_development_dependency 'yajl-ruby',       '~> 1.4'  unless is_java
   gem.add_development_dependency 'rack-test',       '~> 1.1'
   gem.add_development_dependency 'rdf-isomorphic',  '~> 3.0'