Some cleanup around ruby version requirements (#51)

* Use local config instead of polluting gitignore

* Loosen version requirement

* Override rubocop target ruby version

* Update target ruby version in .rubocop.yml

- remove cop override
- eventually we could get a command line option for running the test
suite in different ruby versions: rubocop/rubocop#7557

* Include 2.4 in ruby versions for now to support legacy

Author: adamrdavid

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: [ '2.5', '2.6.x', '2.x']
+        ruby: ['2.4', '2.5', '2.6.x', '2.x']
     name: Test gem in ruby version ${{ matrix.ruby }}
     steps:
     - uses: actions/checkout@v1

.gitignore

@@ -9,5 +9,3 @@
 # https://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
 Gemfile.lock
 
-# ignore version manager files
-.tool-versions

.rubocop.yml

@@ -1,3 +1,6 @@
+AllCops:
+  TargetRubyVersion: 2.4
+
 Style/Documentation:
   Enabled: false
 

.ruby-version

@@ -78,9 +78,9 @@
 
     context 'cwe' do
       it 'has the exepected (concatenated) CWE IDs' do
-        expect(mappings[:cwe]).to eq [
-          'CWE-942',
-          'CWE-933'
+        expect(mappings[:cwe]).to eq %w[
+          CWE-942
+          CWE-933
         ]
       end
     end

spec/vrt/node_spec.rb

@@ -15,7 +15,7 @@ Gem::Specification.new do |spec|
   spec.license       = 'MIT'
   spec.files         = Dir['lib/**/*.{rb,json}']
   spec.require_paths = ['lib']
-  spec.required_ruby_version = '>= 2.5'
+  spec.required_ruby_version = '>= 2.4'
 
   spec.add_development_dependency 'bundler', '~> 2.1'
   spec.add_development_dependency 'pry', '~> 0.11'