Replace archive.dtype with archive.dtypes dict that holds dtype of every field #2433

Job	Run time
pre-commit	1m 2s
examples	3m 27s
test (ubuntu-latest, 3.12)	1m 44s
tutorials_list	3s
test (macos-latest, 3.12)	1m 26s
coverage	1m 52s
test (windows-latest, 3.12)	4m 50s
benchmarks	1m 25s
docs	1m 57s
pin	2m 51s
tutorials (tutorials/arm_repertoire.ipynb)	1m 13s
tutorials (tutorials/cma_mae.ipynb)	8m 22s
tutorials (tutorials/features/example.ipynb)	58s
tutorials (tutorials/fooling_mnist.ipynb)	3m 5s
tutorials (tutorials/lsi_mnist.ipynb)	8m 24s
tutorials (tutorials/lunar_lander.ipynb)	9m 32s
tutorials (tutorials/scalable_cma_mae.ipynb)	4m 32s
deploy	0s
	56m 43s

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