manifest: zephyr update with openthread changes

Pull a Zephyr commit with changes in RxOnWhenIdle OpenThread
handling.

Signed-off-by: Eduardo Montoya <[email protected]>

Author: edmont

west.yml

@@ -63,7 +63,7 @@ manifest:
     # https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/guides/modules.html
     - name: zephyr
       repo-path: sdk-zephyr
-      revision: a1769aba631b078769d182eaaea13aafc09039bc
+      revision: pull/1751/head
       import:
         # In addition to the zephyr repository itself, NCS also
         # imports the contents of zephyr/west.yml at the above