west: Point Zephyr back to main after v3.6.0 release

Points the Zephyr revision back to the main branch after the latest
release, v3.6.0.

Signed-off-by: Maureen Helm <maureen.helm@analog.com>

Author: MaureenHelm

west.yml

@@ -12,7 +12,7 @@ manifest:
   projects:
     - name: zephyr
       remote: zephyrproject-rtos
-      revision: v3.6.0
+      revision: main
       import:
         # By using name-allowlist we can clone only the modules that are
         # strictly needed by the application.