Tests

Support unsorted spectra in `TruncationKeepAbove`/`Below` #147

Job	Run time
Tests (lts, ubuntu-latest) / Julia lts - ubuntu-latest	14m 39s
Tests (lts, windows-latest) / Julia lts - windows-latest	15m 37s
Tests (1, ubuntu-latest) / Julia 1 - ubuntu-latest	17m 0s
Tests (lts, macOS-latest) / Julia lts - macOS-latest	9m 39s
Tests (1, windows-latest) / Julia 1 - windows-latest	19m 7s
Tests (1, macOS-latest) / Julia 1 - macOS-latest	12m 57s
	1h 28m 59s

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