Make audit_casks return [path, { errors:, warnings:}] for CI

- This was failing but only in CI because the annotations require
  "errors" and "warnings" hash elements. Since formulae have this
  despite formulae not having warnings (probably for compatibility with
  casks), I decided to reinstate `errors` and `warnings` hash for Casks
  _right at the end_ and we can clean this up another time (famous last
  words).

Library/Homebrew/cask/cmd/audit.rb

@@ -60,7 +60,7 @@ module Cask
           except:          [],
         )
 
-        failed_casks = results.reject { |_, result| result.empty? }.map(&:first)
+        failed_casks = results.reject { |_, result| result[:errors].empty? }.map(&:first)
         return if failed_casks.empty?
 
         raise CaskError, "audit failed for casks: #{failed_casks.join(" ")}"
@@ -102,7 +102,7 @@ module Cask
 
         casks.to_h do |cask|
           odebug "Auditing Cask #{cask}"
-          [cask.sourcefile_path, Auditor.audit(cask, **options)]
+          [cask.sourcefile_path, { errors: Auditor.audit(cask, **options), warnings: [] }]
         end
       end
     end

Library/Homebrew/dev-cmd/audit.rb

@@ -266,7 +266,7 @@ module Homebrew
       )
     end
 
-    failed_casks = cask_results.reject { |_, result| result.empty? }
+    failed_casks = cask_results.reject { |_, result| result[:errors].empty? }
 
     cask_count = failed_casks.count