add black box marker to hash benchmark #1865

Job	Run time
Wheel on macos-12 py-3.8	2m 47s
Checks	43s
Wheel on ubuntu-latest py-3.8	2m 44s
Run fuzz targets (macos-12, 3.8)	15m 27s
Run fuzz targets (ubuntu-latest, 3.8)	12m 48s
Wheel on windows-latest py-3.8	1m 49s
Unit tests (macos-12, 3.8)	7m 1s
Unit tests (ubuntu-latest, 3.8)	3m 37s
Unit tests (windows-latest, 3.8)	7m 17s
coverage	8m 17s
Upload to PyPI	22s
	1h 2m 52s

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