audit: whitelist bash-completion@* to use conflicts_with

this is necessary because they install conflicting scripts into
HOMEBREW_PREFIX/etc/profile.d

Library/Homebrew/dev-cmd/audit.rb

@@ -532,8 +532,11 @@ class FormulaAuditor
       end
     end
 
+    versioned_conflicts_whitelist = %w[node@ bash-completion@]
+
     return unless formula.conflicts.any? && formula.versioned_formula?
-    return if formula.name.start_with? "node@"
+    versioned_conflicts_whitelist.each { |c|
+      return if formula.name.start_with? c }
     problem <<-EOS
       Versioned formulae should not use `conflicts_with`.
       Use `keg_only :versioned_formula` instead.