Wrap service command parameters in single quotes

Should resolve issues with multi-word arguments, eg:

> Or, if you don't want/need a background service you can just run:
  /opt/homebrew/opt/nginx/bin/nginx -g daemon off;

fails, but 

> Or, if you don't want/need a background service you can just run:
  '/opt/homebrew/opt/nginx/bin/nginx' '-g' 'daemon off;'

succeeds

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

@@ -37,7 +37,7 @@ class Caveats
 
     if f.plist_manual || f.service?
       command = if f.service?
-        f.service.command.join(" ")
+        f.service.command.map{ |arg| "'#{arg}'" }.join(" ")
       else
         f.plist_manual
       end