Unbreak breaking change for `ZNIrrep` (#37) #207

Job	Run time
Julia lts - windows-latest - push	7m 35s
Julia lts - macOS-latest - push	6m 4s
Julia 1 - macOS-latest - push	8m 53s
Julia lts - ubuntu-latest - push	5m 18s
Julia 1 - ubuntu-latest - push	8m 27s
Julia 1 - windows-latest - push	9m 4s
	45m 21s

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