Change way to describe bound for DSP.jl #33

Job	Run time
test (nightly, x64, ubuntu-latest)	2m 24s
test (1.6, x64, ubuntu-latest)	1m 26s
test (1.6, x86, windows-latest)	11m 11s
test (1.6, x64, macOS-latest)	1m 46s
test (1, x64, macOS-latest)	2m 47s
test (1.6, x86, ubuntu-latest)	1m 47s
test (1.6, x64, windows-latest)	18m 42s
test (1, x86, ubuntu-latest)	2m 45s
test (1, x64, ubuntu-latest)	2m 17s
test (nightly, x64, windows-latest)	3m 52s
test (nightly, x64, macOS-latest)	2m 56s
test (1, x64, windows-latest)	3m 14s
test (1, x86, windows-latest)	4m 7s
test (nightly, x86, ubuntu-latest)	3m 2s
test (nightly, x86, windows-latest)	3m 50s
	1h 6m 6s

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