Switch from cancan to cancancan

Development of cancan stopped in 2013. cancancan is the active fork of the defunct original, and has been updated many times to keep up with changes in newer Rails and Ruby versions.

Gemfile

@@ -23,7 +23,7 @@ gem 'pg', '~> 0.21.0'
 
 gem 'acts_as_list', '0.9.19'
 gem 'awesome_nested_set', '~> 3.3.1'
-gem 'cancan', '~> 1.6.10'
+gem 'cancancan', '~> 1.7.0'
 gem 'ffaker'
 gem 'highline', '2.0.3' # Necessary for the install generator
 gem 'json'

Gemfile.lock

@@ -131,7 +131,7 @@ GEM
       concurrent-ruby (~> 1.0)
     builder (3.2.4)
     byebug (11.1.3)
-    cancan (1.6.10)
+    cancancan (1.7.1)
     capybara (3.32.2)
       addressable
       mini_mime (>= 0.1.3)
@@ -737,7 +737,7 @@ DEPENDENCIES
   aws-sdk (= 1.67.0)
   bugsnag
   byebug
-  cancan (~> 1.6.10)
+  cancancan (~> 1.7.0)
   capybara
   catalog!
   coffee-rails (~> 4.2.2)