Tests

various fixes and improvements #4

Job	Run time
Tests (lts, macOS-latest) / Julia lts - macOS-latest	23s
Tests (1, ubuntu-latest) / Julia 1 - ubuntu-latest	4m 23s
Tests (1, windows-latest) / Julia 1 - windows-latest	5m 40s
Tests (1, macOS-latest) / Julia 1 - macOS-latest	3m 56s
Tests (lts, ubuntu-latest) / Julia lts - ubuntu-latest	23s
Tests (lts, windows-latest) / Julia lts - windows-latest	41s
	15m 26s

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