Update Zephyr to v4.0 #98

Job	Run time
build (ubuntu-latest, examples/mbed-rtos-blink-baremetal)	1m 17s
build (ubuntu-latest, examples/mbed-rtos-cellular)	2m 38s
build (ubuntu-latest, examples/mbed-rtos-ethernet-tls)	2m 34s
build (ubuntu-latest, examples/zephyr-blink)	2m 29s
build (ubuntu-latest, examples/zephyr-synchronization)	2m 34s
build (windows-latest, examples/mbed-rtos-blink-baremetal)	4m 31s
build (windows-latest, examples/mbed-rtos-cellular)	11m 30s
build (windows-latest, examples/mbed-rtos-ethernet-tls)	12m 31s
build (windows-latest, examples/zephyr-blink)	9m 1s
build (windows-latest, examples/zephyr-synchronization)	7m 41s
build (macos-latest, examples/mbed-rtos-blink-baremetal)	2m 20s
build (macos-latest, examples/mbed-rtos-cellular)	6m 13s
build (macos-latest, examples/mbed-rtos-ethernet-tls)	6m 11s
build (macos-latest, examples/zephyr-blink)	3m 9s
build (macos-latest, examples/zephyr-synchronization)	2m 41s
	1h 17m 20s

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