manifest: Update sdk-zephyr to have GRTC and timer tests for nRF54L20#20141

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

adamkondraciuk:NRFX-5891-Run-Zephyr-system-timer-tests-for-nRF54L20adamkondraciuk/sdk-nrf:NRFX-5891-Run-Zephyr-system-timer-tests-for-nRF54L20Copy head branch name to clipboard