Set ruby v2.3 as minimum ruby version

apexcharts.gemspec

@@ -5,16 +5,17 @@ $LOAD_PATH.push File.expand_path('lib', __dir__)
 require_relative 'lib/apex_charts/version'
 
 Gem::Specification.new do |spec|
-  spec.name        = 'apexcharts'
-  spec.version     = ApexCharts::VERSION
-  spec.authors     = ['Adrian Setyadi']
-  spec.email       = ['a.styd@yahoo.com']
-  spec.homepage    = 'https://github.com/styd/apexcharts.rb'
-  spec.summary     = 'Awesome charts for your ruby app'
-  spec.description =
+  spec.name                  = 'apexcharts'
+  spec.version               = ApexCharts::VERSION
+  spec.required_ruby_version = ApexCharts::REQUIRED_RUBY_VERSION
+  spec.authors               = ['Adrian Setyadi']
+  spec.email                 = ['a.styd@yahoo.com']
+  spec.homepage              = 'https://github.com/styd/apexcharts.rb'
+  spec.summary               = 'Awesome charts for your ruby app'
+  spec.description           =
     'Create beautiful, interactive, and responsive web charts in ' \
     'ruby app powered by apexcharts.js.'
-  spec.license     = 'MIT'
+  spec.license               = 'MIT'
 
   spec.files = `git ls-files -z`.split("\x0").reject do |f|
     f.match(%r{^(docs|images|spec|\.github)/})

lib/apex_charts/version.rb

@@ -3,4 +3,5 @@
 module ApexCharts
   VERSION = '0.2.0'
   RELEASE = '0.2.0'
+  REQUIRED_RUBY_VERSION = '>= 2.3.0'
 end