refactor!: update minimum Ruby version to 3.0

activeadmin_quill_editor.gemspec

@@ -14,7 +14,7 @@ Gem::Specification.new do |spec|
   spec.email         = 'mat@blocknot.es'
   spec.homepage      = 'https://github.com/blocknotes/activeadmin_quill_editor'
 
-  spec.required_ruby_version = '>= 2.6.0'
+  spec.required_ruby_version = '>= 3.0'
 
   spec.metadata['homepage_uri']    = spec.homepage
   spec.metadata['changelog_uri']   = 'https://github.com/blocknotes/activeadmin_quill_editor/blob/main/CHANGELOG.md'
@@ -27,5 +27,5 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency 'activeadmin', '>= 2.0', '< 4'
 
-  spec.add_development_dependency 'appraisal', '~> 2.4'
+  spec.add_development_dependency 'appraisal', '~> 2.4' # rubocop:disable Gemspec/DevelopmentDependencies
 end