remove support for ruby versions < 2.3

Author: majormoses

CHANGELOG.md

@@ -5,6 +5,9 @@ This CHANGELOG follows the format listed [here](https://github.com/sensu-plugins
 
 ## [Unreleased]
 
+### Breaking Changes
+- removed ruby support for versions `< 2.3` (@majormoses)
+
 ## [2.1.0] - 2018-05-23
 ### Added
 - check-es-shard-allocation-status.rb, check-es-file-descriptors.rb, check-es-heap.rb: added `--cert-file` option which allows you to specify a ca-cert to be used to verify TLS (@vin01)

sensu-plugins-elasticsearch.gemspec

@@ -26,7 +26,7 @@ Gem::Specification.new do |s| # rubocop:disable Metrics/BlockLength
   s.platform               = Gem::Platform::RUBY
   s.post_install_message   = 'You can use the embedded Ruby by setting EMBEDDED_RUBY=true in /etc/default/sensu'
   s.require_paths          = ['lib']
-  s.required_ruby_version  = '>= 2.1.0'
+  s.required_ruby_version  = '>= 2.3.0'
   # s.signing_key            = File.expand_path(pvt_key) if $PROGRAM_NAME =~ /gem\z/
   s.summary                = 'Sensu plugins for elasticsearch'
   s.test_files             = s.files.grep(%r{^(test|spec|features)/})