Allow mongoid 7

Author: boie0025

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',     ['~> 6.0']
+  gem.add_runtime_dependency 'mongoid',     '>= 6.0', '< 8.a'
   gem.add_runtime_dependency 'activeadmin', '>= 1.3.0'
   gem.add_runtime_dependency 'jquery-rails'
   gem.add_runtime_dependency 'sass-rails',  ['>= 3.1.4']