manifest: update sdk-zephyr with LFCLK rework

Part of nrfx 4.0.

Signed-off-by: Marcin Szymczyk <[email protected]>

Author: masz-nordic

west.yml

@@ -66,7 +66,7 @@ manifest:
     # https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/guides/modules.html
     - name: zephyr
       repo-path: sdk-zephyr
-      revision: 3639fc35c554391386a1a6e6ea3067499f0f1fd1
+      revision: a0491b6ceaf072ff7fa108ecfeddb7cbc6c3afa7
       import:
         # In addition to the zephyr repository itself, NCS also
         # imports the contents of zephyr/west.yml at the above