test: Remove Appraisal dependency

Appraisals

@@ -1,33 +0,0 @@
-# frozen_string_literal: true
-
-appraise 'rails61-activeadmin29' do
-  gem 'activeadmin', '~> 2.9.0'
-  gem 'rails', '~> 6.1.0'
-end
-
-appraise 'rails61-activeadmin' do
-  gem 'activeadmin'
-  gem 'rails', '~> 6.1.0'
-end
-
-appraise 'rails70-activeadmin' do
-  gem 'activeadmin'
-  gem 'rails', '~> 7.0.0'
-
-  gem 'sqlite3', '~> 1.3'
-end
-
-appraise 'rails71-activeadmin' do
-  gem 'activeadmin'
-  gem 'rails', '~> 7.1.0'
-end
-
-appraise 'rails72-activeadmin' do
-  gem 'activeadmin'
-  gem 'rails', '~> 7.2.0'
-end
-
-appraise 'rails80-activeadmin' do
-  gem 'activeadmin'
-  gem 'rails', '~> 8.0.0'
-end