Update writing.md: Add FileIO dependency #308

Job	Run time
test (ubuntu-latest, x64, 1.6)	3m 36s
test (ubuntu-latest, x64, 1)	3m 14s
test (ubuntu-latest, x64, nightly)	4m 44s
test (ubuntu-latest, x86, 1.6)	3m 33s
test (ubuntu-latest, x86, 1)	3m 6s
test (ubuntu-latest, x86, nightly)	4m 51s
test (macOS-13, x64, 1.6)	5m 34s
test (macOS-13, x64, 1)	6h 0m 18s
test (macOS-13, x64, nightly)	6m 19s
test (macOS-14, aarch64, 1)	2m 58s
test (macOS-14, aarch64, nightly)	4m 10s
test (windows-latest, x64, 1.6)	8m 33s
test (windows-latest, x64, 1)	4m 7s
test (windows-latest, x64, nightly)	5m 52s
test (windows-latest, x86, 1.6)	7m 20s
test (windows-latest, x86, 1)	4m 5s
test (windows-latest, x86, nightly)	6m 14s
	7h 18m 34s

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