Drop to support Ruby 2.2 because rubygems.org will not support V1 API and bundler 1.x

Author: hsbt

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
   ruby-versions:
     uses: ruby/actions/.github/workflows/ruby_versions.yml@master
     with:
-      min_version: 2.2
+      min_version: 2.3
       engine: cruby-jruby
       versions: '["truffleruby"]'
 

rake.gemspec

@@ -95,6 +95,6 @@ Rake has the following features:
   s.executables = s.files.grep(%r{^exe/}) { |f| File.basename(f) }
   s.require_paths = ["lib".freeze]
 
-  s.required_ruby_version = Gem::Requirement.new(">= 2.2".freeze)
+  s.required_ruby_version = Gem::Requirement.new(">= 2.3".freeze)
   s.rdoc_options = ["--main".freeze, "README.rdoc".freeze]
 end