Relax Rails version constraint for use with Rails 6+

Contraint was unnecessarily strict as Orchid works with Rails 6

Author: techgique

lib/orchid/version.rb

@@ -1,3 +1,3 @@
 module Orchid
-  VERSION = '3.1.1'
+  VERSION = '3.1.2'
 end

orchid.gemspec

@@ -16,7 +16,7 @@ Gem::Specification.new do |s|
 
   s.files = Dir["{app,config,db,lib}/**/*", "MIT-LICENSE", "Rakefile", "README.md"]
 
-  s.add_dependency "rails", "~> 5.2.0"
+  s.add_dependency "rails", ">5.2.0", "<7.0"
 
   s.add_development_dependency "sqlite3"
 end