Update mongoid to version 7.0.1

Author: depfu[bot]

activeadmin-mongoid.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |gem|
   gem.version       = ActiveAdmin::Mongoid::VERSION
   gem.license       = 'MIT'
 
-  gem.add_runtime_dependency 'mongoid',     ['> 3.0', '< 5.0']
+  gem.add_runtime_dependency 'mongoid',     ['> 3.0', '<= 7.0.1']
   gem.add_runtime_dependency 'activeadmin', ['>= 1.0.0.pre', '< 2']
   gem.add_runtime_dependency 'jquery-rails'
   gem.add_runtime_dependency 'sass-rails',  ['>= 3.1.4', '< 5.0']