Update Library/Homebrew/extend/os/mac/caveats.rb

Co-authored-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/extend/os/mac/caveats.rb

@@ -7,7 +7,7 @@ class Caveats
   def plist_caveats
     s = []
     if !f.plist && !f.service? && !keg&.plist_installed?
-      caveat = "#{s.join("\n")}\n" unless s.empty?
+      caveat = "#{s.join("\n")}\n" if s.present?
       return caveat
     end