Add Einstein-Helfand viscosity implementation #82

Job	Run time
environment-config	3s
pylint_check	37s
pypi_check	25s
black_check	11s
main-tests (macOS-latest, 3.9, latest)	5m 25s
main-tests (macOS-latest, 3.9, develop)	10m 28s
main-tests (macOS-latest, 3.10, latest)	8m 19s
main-tests (macOS-latest, 3.10, develop)	12m 52s
main-tests (macOS-latest, 3.11, latest)	4m 37s
main-tests (macOS-latest, 3.11, develop)	8m 7s
main-tests (ubuntu-latest, 3.9, latest)	2m 44s
main-tests (ubuntu-latest, 3.9, develop)	4m 5s
main-tests (ubuntu-latest, 3.10, latest)	2m 14s
main-tests (ubuntu-latest, 3.10, develop)	4m 46s
main-tests (ubuntu-latest, 3.11, latest)	2m 40s
main-tests (ubuntu-latest, 3.11, develop)	3m 52s
main-tests (windows-latest, 3.9, latest)	7m 35s
main-tests (windows-latest, 3.9, develop)	11m 32s
main-tests (windows-latest, 3.10, latest)	9m 39s
main-tests (windows-latest, 3.10, develop)	12m 59s
main-tests (windows-latest, 3.11, latest)	8m 41s
main-tests (windows-latest, 3.11, develop)	13m 16s
	2h 15m 7s

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