audit: freeze versioned_conflicts_whitelist

Library/Homebrew/dev-cmd/audit.rb

@@ -532,7 +532,7 @@ class FormulaAuditor
       end
     end
 
-    versioned_conflicts_whitelist = %w[node@ bash-completion@]
+    versioned_conflicts_whitelist = %w[node@ bash-completion@].freeze
 
     return unless formula.conflicts.any? && formula.versioned_formula?
     return if formula.name.start_with?(*versioned_conflicts_whitelist)