Lock cancancan to 3.5.x as 3.6 doesn't work in Ruby 2.6 and JRuby 9.3

Refs. CanCanCommunity/cancancan#851

Author: mshibuya

Appraisals

@@ -6,7 +6,7 @@ appraise 'rails-6.0' do
   gem 'devise', '~> 4.7'
 
   group :test do
-    gem 'cancancan', '~> 3.0'
+    gem 'cancancan', ['~> 3.0', '< 3.6']
     gem 'kt-paperclip'
     gem 'pundit', '~> 2.1.0'
     gem 'rspec-rails', '>= 4.0.0.beta2'
@@ -40,7 +40,7 @@ appraise 'rails-6.1' do
   gem 'devise', '~> 4.7'
 
   group :test do
-    gem 'cancancan', '~> 3.2'
+    gem 'cancancan', ['~> 3.2', '< 3.6']
     gem 'kt-paperclip'
     gem 'rspec-rails', '>= 4.0.0.beta2'
     gem 'shrine', '~> 3.0'

gemfiles/rails_6.0.gemfile

@@ -31,7 +31,7 @@ group :development, :test do
 end
 
 group :test do
-  gem "cancancan", "~> 3.0"
+  gem "cancancan", ["~> 3.0", "< 3.6"]
   gem "carrierwave", [">= 2.0.0.rc", "< 3"]
   gem "cuprite"
   gem "database_cleaner-active_record", ">= 2.0", require: false

gemfiles/rails_6.1.gemfile

@@ -31,7 +31,7 @@ group :development, :test do
 end
 
 group :test do
-  gem "cancancan", "~> 3.2"
+  gem "cancancan", ["~> 3.2", "< 3.6"]
   gem "carrierwave", [">= 2.0.0.rc", "< 3"]
   gem "cuprite"
   gem "database_cleaner-active_record", ">= 2.0", require: false