test: Remove Appraisal dependency

activeadmin_quill_editor.gemspec

@@ -26,6 +26,4 @@ Gem::Specification.new do |spec|
   spec.require_paths = ['lib']
 
   spec.add_runtime_dependency 'activeadmin', '>= 2.9', '< 4' # rubocop:disable Gemspec/AddRuntimeDependency
-
-  spec.add_development_dependency 'appraisal', '~> 2.4' # rubocop:disable Gemspec/DevelopmentDependencies
 end