upgrade landmarks to 1.5, add cachet #5589

Job	Run time
nix-fmt-check	1m 43s
Native packages (macOS (macos-13), OCaml 5_1)	17m 58s
Native packages (macOS (macos-13), OCaml 5_2)	17m 34s
Native packages (Linux, OCaml 4_14)	1m 52s
arm64 packages (OCaml 4_14)	1m 46s
Native packages (macOS (macos-13), OCaml 5_3)	26m 25s
Native (Top-level) packages (ubuntu-latest)	1m 34s
Native packages (Linux, OCaml 5_1)	2m 15s
musl packages (OCaml 4_14)	1m 25s
Native packages (macOS (macos-14), OCaml 4_14)	7m 41s
Native (Top-level) packages (macos-13)	4m 25s
Native packages (Linux, OCaml 5_2)	2m 0s
arm64 packages (OCaml 5_1)	1m 36s
Native packages (macOS (macos-14), OCaml 5_1)	10m 7s
Native packages (Linux, OCaml 5_3)	2m 48s
Native (Top-level) packages (macos-14)	2m 29s
musl packages (OCaml 5_1)	1m 32s
Native packages (macOS (macos-14), OCaml 5_2)	7m 58s
arm64 packages (OCaml 5_2)	2m 47s
Native packages (macOS (macos-14), OCaml 5_3)	9m 42s
musl packages (OCaml 5_2)	2m 0s
arm64 packages (OCaml 5_3)	1m 45s
musl packages (OCaml 5_3)	3m 4s
	2h 12m 26s

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