Update documentation, dependencies, and version sync for 0.3.

Author: gkellogg

.github/workflows/ci.yml

@@ -20,9 +20,9 @@ jobs:
       fail-fast: false
       matrix:
         ruby:
-          - 2.5
           - 2.6
           - 2.7
+          - 3.0
           - ruby-head
           - jruby
     steps:

README.md

@@ -67,8 +67,8 @@ Full documentation available on [RubyDoc](http://rubydoc.info/gems/json-canonica
 * {JSON::Canonicalization}
 
 ## Dependencies
-* [Ruby](http://ruby-lang.org/) (>= 2.4)
-* [JSON](https://rubygems.org/gems/json) (>= 2.3)
+* [Ruby](http://ruby-lang.org/) (>= 2.6)
+* [JSON](https://rubygems.org/gems/json) (>= 2.6)
 
 ## Author
 * [Gregg Kellogg](http://github.com/gkellogg) - <http://kellogg-assoc.com/>

VERSION

@@ -1 +1 @@
-0.2.1
+0.3.0

json-canonicalization.gemspec

@@ -17,7 +17,7 @@ Gem::Specification.new do |gem|
   gem.files                 = %w(AUTHORS README.md LICENSE VERSION) + Dir.glob('lib/**/*.rb')
   gem.test_files            = Dir.glob('spec/**/*.rb') + Dir.glob('spec/**/*.json')
 
-  gem.required_ruby_version = '>= 2.4'
+  gem.required_ruby_version = '>= 2.6'
   gem.requirements          = []
   gem.add_development_dependency 'rspec',           '~> 3.10'
   gem.add_development_dependency 'yard' ,           '~> 0.9'