Fix RuboCop offense Style/StringChars (#39887).

git-svn-id: https://svn.redmine.org/redmine/trunk@23009 e93f8b46-1217-0410-a6f0-8f06a7374b81

.rubocop_todo.yml

@@ -1271,11 +1271,6 @@ Style/StderrPuts:
     - 'config/environment.rb'
     - 'config/initializers/10-patches.rb'
 
-# This cop supports unsafe autocorrection (--autocorrect-all).
-Style/StringChars:
-  Exclude:
-    - 'app/models/user.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: Mode.
 Style/StringConcatenation:

app/models/user.rb

@@ -371,7 +371,7 @@ class User < Principal
     end
     chars = chars_list.flatten
     length.times {password << chars[SecureRandom.random_number(chars.size)]}
-    password = password.split('').shuffle(random: SecureRandom).join
+    password = password.chars.shuffle(random: SecureRandom).join
     self.password = password
     self.password_confirmation = password
     self