manifest: update sdk-zephyr with LFXO for GRTC#17217

adamkondraciuk wants to merge 1 commit intonrfconnect:mainnrfconnect/sdk-nrf:mainfrom

adamkondraciuk:NRFX-6304-switch-GRTC-source-to-LFXOadamkondraciuk/sdk-nrf:NRFX-6304-switch-GRTC-source-to-LFXOCopy head branch name to clipboard