croupier: Fix ETHER_DIR

Simple switch to use the new release/mojo/syncbase directory

Change-Id: I939cafbad9644633dfb7fbeb7db51a301cf64ed2
diff --git a/Makefile b/Makefile
index 27f166e..4072204 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 # This beginning section is used to setup the environment for running with mojo_shell.
-ETHER_DIR := $(V23_ROOT)/roadmap/mojo/syncbase
+ETHER_DIR := $(V23_ROOT)/release/mojo/syncbase
 CROUPIER_DIR := $(shell pwd)
 SHELL := /bin/bash -euo pipefail