add friction model "Hofer" #1623

Job	Run time
Linting	14s
Sphinx docs check	29s
Tutorial tests (3.9, ubuntu-latest)	1m 27s
Tests (3.9, ubuntu-latest)	42s
Tutorial tests (3.9, windows-latest)	2m 41s
Tests (3.9, windows-latest)	1m 14s
Tutorial tests (3.10, ubuntu-latest)	1m 18s
Tests (3.10, ubuntu-latest)	45s
Tutorial tests (3.10, windows-latest)	2m 7s
Tests (3.10, windows-latest)	1m 34s
Tutorial tests (3.11, ubuntu-latest)	1m 32s
Tests (3.11, ubuntu-latest)	1m 1s
Tutorial tests (3.11, windows-latest)	2m 28s
Tests (3.11, windows-latest)	1m 48s
Tutorial tests (3.12, ubuntu-latest)	1m 10s
Tests (3.12, ubuntu-latest)	38s
Tutorial tests (3.12, windows-latest)	1m 55s
Tests (3.12, windows-latest)	1m 11s
	24m 14s

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