Prep for 3.1 release.

* Update VERSION to 3.1.0.
* Remove 2.2 and 2.3 Ruby versions from travis config
* require Ruby >= 2.4 in gemspec

Author: gkellogg

.travis.yml

@@ -1,23 +1,16 @@
 language: ruby
-bundler_args: --without debug
 script: "bundle exec rspec spec"
-before_install: 
-  - 'gem update --system --conservative || (gem i "rubygems-update:~>2.7" --no-document && update_rubygems)'
-  - 'gem update bundler --conservative'
 env:
   - CI=true
 rvm:
-  - 2.2.2
-  - 2.3
   - 2.4
   - 2.5
   - 2.6
-  - jruby-9
-  - rbx-3
+  - 2.7
+  - jruby
 cache: bundler
 sudo: false
 matrix:
   allow_failures:
-    - rvm: jruby-9
-    - rvm: rbx-3
+    - rvm: jruby
 dist: trusty

VERSION

@@ -1 +1 @@
-3.0.0
+3.1.0

rdf-spec.gemspec

@@ -18,13 +18,13 @@ Gem::Specification.new do |gem|
   gem.files              = %w(AUTHORS CREDITS README.md UNLICENSE VERSION) + Dir.glob('etc/*') + Dir.glob('lib/**/*.rb') + Dir.glob('spec/*.rb')
   gem.require_paths      = %w(lib)
 
-  gem.required_ruby_version      = '>= 2.2.2'
+  gem.required_ruby_version      = '>= 2.4'
   gem.requirements               = []
-  gem.add_runtime_dependency     'rdf',             '~> 3.0'
+  gem.add_runtime_dependency     'rdf',             '~> 3.1'
   gem.add_runtime_dependency     'rdf-isomorphic',  '~> 3.0'
-  gem.add_runtime_dependency     'rspec',           '~> 3.7'
-  gem.add_runtime_dependency     'rspec-its',       '~> 1.2'
-  gem.add_runtime_dependency     'webmock',         '~> 3.1'
-  gem.add_development_dependency 'yard' ,           '~> 0.9.12'
+  gem.add_runtime_dependency     'rspec',           '~> 3.9'
+  gem.add_runtime_dependency     'rspec-its',       '~> 1.3'
+  gem.add_runtime_dependency     'webmock',         '~> 3.7'
+  gem.add_development_dependency 'yard' ,           '~> 0.9.20'
   gem.post_install_message       = nil
 end