adding underscore in artunc key #1014

Job	Run time
run_pytorch	4m 33s
regression_tests	4m 57s
run_jax	2m 36s
conda_tests (ubuntu-latest)	25m 9s
run_package_tests (macos-14, 3.13)	38m 19s
run_package_tests (ubuntu-latest, 3.13)	43m 33s
run_package_tests (macos-14, 3.10)	46m 53s
conda_tests (macos-14)	25m 20s
run_package_tests (ubuntu-latest, 3.10)	42m 28s
full_coverage	0s
	3h 53m 48s

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