Pump papertrail gem to 8.1

Gemfile

@@ -10,11 +10,11 @@ gem 'uglifier'
 gem 'figaro', '1.1.1'
 
 # model related
+gem 'paper_trail', '~> 8.1'
 gem 'pg',                        '1.2.2'
 # 1.8 is for Rails < 5.0
 gem 'ransack', '~> 1.8'
 gem 'validates_email_format_of', '1.6.3' # validates email against RFC 2822 and RFC 3696
-gem 'paper_trail', '~> 6.0'
 
 # 0.7.3 is the latest for Rails 4.2, however, it is absent on Rubygems server
 # https://github.com/huacnlee/rails-settings-cached/issues/165

Gemfile.lock

@@ -272,8 +272,8 @@ GEM
     nori (2.6.0)
     open4 (1.3.4)
     orm_adapter (0.5.0)
-    paper_trail (6.0.2)
+    paper_trail (8.1.2)
-      activerecord (>= 4.0, < 5.2)
+      activerecord (>= 4.2, < 5.2)
       request_store (~> 1.1)
     pdfkit (0.8.4.1)
     pg (1.2.2)
@@ -481,7 +481,7 @@ DEPENDENCIES
   minitest (~> 5.14)
   money-rails
   nokogiri
-  paper_trail (~> 6.0)
+  paper_trail (~> 8.1)
   pdfkit
   pg (= 1.2.2)
   pry (= 0.10.1)

app/models/concerns/versions.rb

@@ -45,11 +45,11 @@ module Versions
 
     # callbacks
     def touch_domain_version
-      domain.try(:touch_with_version)
+      domain.paper_trail.try(:touch_with_version)
     end
 
     def touch_domains_version
-      domains.each(&:touch_with_version)
+      domains.each { |domain| domain.paper_trail.touch_with_version }
     end
   end