west.yml: update Zephyr to c50777a84311 #704

Job	Run time
build-linux (mnfst, imx8 imx8x imx8m imx8ulp)	34s
build-linux (mnfst, mtl)	34s
build-windows (imx8 imx8x imx8m imx8ulp)	21s
build-linux (mnfst, lnl)	35s
build-windows (mtl)	22s
build-linux (mnfst, tgl tgl-h)	35s
build-windows (tgl tgl-h)	20s
build-linux (zmain, imx8 imx8x imx8m imx8ulp)	33s
build-windows (-d, mtl)	21s
build-linux (zmain, mtl)	32s
LP64-WIP	35s
build-linux (zmain, lnl)	32s
manifest-check	35s
build-linux (zmain, tgl tgl-h)	33s
build-linux (-d, mnfst, mtl)	34s
build-linux (mnfst, --all)	35s
compare-linux-win	13s
	8m 24s

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