Replace `ReprMixin` with dataclasses #4926

Job	Run time
build-windows (3.8)	13m 36s
build-ubuntu (3.8, Repository only)	2m 43s
build-ubuntu (3.8, Everything else)	7m 41s
build-ubuntu (3.8, torch)	3m 38s
build-ubuntu (3.11, Repository only)	2m 49s
build-ubuntu (3.11, Everything else)	8m 7s
build-ubuntu (3.11, torch)	3m 13s
build-ubuntu (3.11, lfs)	1m 38s
build-ubuntu (3.8, fastai)	4m 1s
build-ubuntu (3.10, fastai)	3m 38s
build-ubuntu (3.8, tensorflow)	1m 47s
build-ubuntu (3.10, tensorflow)	3m 4s
	55m 55s

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