chore: use serde_json::from_str #758

Job	Run time
doctest	1m 34s
clippy	1m 7s
feature-checks	3m 9s
docs	38s
fmt	11s
test stable (ubuntu-latest)	1m 13s
test stable --all-features (ubuntu-latest)	2m 14s
test 1.70 (ubuntu-latest)	43s
test stable (macos-latest)	1m 11s
test stable --all-features (macos-latest)	2m 27s
test 1.70 (macos-latest)	1m 14s
test stable (windows-latest)	3m 1s
test stable --all-features (windows-latest)	5m 6s
test 1.70 (windows-latest)	2m 13s
	26m 1s

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