Update update-stack.sh

Author: Pelirrojo

scripts/update-stack.sh

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+aws --version >/dev/null 2>&1 || { echo >&2 "I require aws cli but it's not installed. ¯\_(ツ)_/¯ Aborting."; exit 1; }
+
 # Creates the stack
 
 set -e