Tests

Swap to using nn.Embedding #441

Job	Run time
tests (macos-14, 3.12, lowest-direct)	4m 57s
tests (ubuntu-latest, 3.10, highest)	6m 17s
tests (macos-14, 3.10, highest)	4m 44s
tests (ubuntu-latest, 3.12, lowest-direct)	6m 23s
	22m 21s

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