Update `softbuffer` dependency. #97

Job	Run time
miri	1m 44s
build (ubuntu, stable, locked, true)	11m 27s
build (windows, stable, locked, false)	11m 14s
build (macos, stable, locked, false)	11m 23s
build (ubuntu, nightly, locked, false)	7m 15s
build (ubuntu, beta, locked, false)	5m 52s
build (ubuntu, stable, latest, false)	11m 27s
build (ubuntu, stable, minimal, false)	11m 35s
fuzz	1s
deploy	1s
	1h 11m 59s

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