Adding Greenpass to USERS list (#3699)

Author: edernucci

USERS.md

@@ -23,6 +23,7 @@ Currently, the following organizations are **officially** using Argo CD:
 1. [Fave](https://myfave.com)
 1. [Future PLC](https://www.futureplc.com/)
 1. [GMETRI](https://gmetri.com/)
+1. [Greenpass](https://www.greenpass.com.br/)
 1. [Healy](https://www.healyworld.net)
 1. [hipages](https://hipages.com.au/)
 1. [Honestbank](https://honestbank.com)