cmd/casks: use ShellCommand

Library/Homebrew/cmd/casks.rb

@@ -2,18 +2,18 @@
 # frozen_string_literal: true
 
 require "abstract_command"
+require "shell_command"
 
 # This Ruby command exists to allow generation of completions for the Bash
 # version. It is not meant to be run.
 module Homebrew
   module Cmd
     class Casks < AbstractCommand
+      include ShellCommand
+
       cmd_args do
         description "List all locally installable casks including short names."
       end
-
-      sig { override.void }
-      def run = raise_sh_command_error!
     end
   end
 end