feat: support Ruby 2.6 and 2.7

.github/workflows/checks.yml

@@ -21,7 +21,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
-        ruby: ['3.0', '3.1', head]
+        ruby: ['2.6', '2.7', '3.0', '3.1', head]
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout
@@ -42,6 +42,6 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '3.0'
+          ruby-version: '2.6'
           bundler-cache: true
       - run: bundle exec rubocop

.rubocop.yml

@@ -14,7 +14,7 @@ AllCops:
   NewCops: enable
   DisplayCopNames: true
   DisplayStyleGuide: true
-  TargetRubyVersion: 3.0
+  TargetRubyVersion: 2.6
   Exclude:
     - 'bin/*'
     - 'node_modules/**/*'

package_json.gemspec

@@ -12,7 +12,7 @@ Gem::Specification.new do |spec|
   spec.description = "It does stuff"
   spec.homepage = "https://github.com/G-Rath/package_json"
   spec.license = "MIT"
-  spec.required_ruby_version = ">= 3.0.0"
+  spec.required_ruby_version = ">= 2.6.0"
 
   spec.metadata["allowed_push_host"] = "TODO: Set to your gem server 'https://example.com'"