Fix dask statistics #1017

Job	Run time
Py3.10 mindeps	5m 44s
Py3.11 mindeps	6m 32s
Py3.12 mindeps	7m 6s
Py3.11 no visualization + coverage	8m 59s
Py3.8 mindeps	3m 16s
Py3.9 noviz	5m 50s
Py3.9 all	6m 13s
Py3.11 dev	8m 58s
Py3.11 viz	7m 31s
Py3.11 all dev	9m 18s
Py3.8 mindeps and CASA	4m 24s
Py3.10 mindeps and CASA	7m 6s
Py3.11, noviz, dev	9m 21s
Py3.8 noviz (except CASA)	3m 56s
Py3.11 noviz (except CASA) MacOS X	3m 33s
Py3.11, noviz Windows	14m 36s
Py3.11, noviz, dev; Windows	14m 39s
Documentation	1m 23s
	2h 8m 25s

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