Fix dep: `once_cell` is needed on all targets #1421

Job	Run time
Test CUDA support	24s
Test build-std (aarch64-tvos)	2m 54s
Test build-std (aarch64-tvos-sim)	4m 42s
Clippy	22s
Test build-std (x86_64-tvos)	4m 38s
MSRV (ubuntu-latest)	31s
Rustfmt	11s
MSRV (windows-latest)	45s
Test (stable)	41s
Test (beta)	40s
Test (nightly)	38s
Test (linux32)	1m 23s
Test (macos)	2m 4s
Test (aarch64-macos)	52s
Test (aarch64-ios)	1m 21s
Test (win32)	1m 27s
Test (win64)	2m 9s
Test (mingw32)	1m 48s
Test (mingw64)	1m 48s
Test (windows-2019)	2m 35s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	2m 12s
Test (windows-clang, windows-2019, stable, x86_64-pc-windows-msvc, clang, clang++)	3m 17s
Test (windows-clang-cl, windows-2019, stable, x86_64-pc-windows-msvc, clang-cl, clang-cl)	2m 26s
	39m 48s

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