refactor: replace `pydantic_core.from_json` by `json.loads` #214

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	33s
checks / test (3.11, locked, windows-latest)	2m 34s
checks / test (3.12, lowest-direct, windows-latest)	3m 39s
checks / test (3.13, lowest-direct, ubuntu-latest)	46s
checks / test (3.12, lowest-direct, ubuntu-latest)	51s
checks / test (3.11, lowest-direct, windows-latest)	2m 28s
checks / test (3.13, locked, ubuntu-latest)	42s
checks / test (3.10, locked, ubuntu-latest)	42s
checks / test (3.14, locked, windows-latest)	3m 0s
checks / test (3.10, locked, windows-latest)	2m 25s
checks / test (3.14, locked, ubuntu-latest)	2m 20s
checks / test (3.11, locked, ubuntu-latest)	48s
checks / test (3.12, locked, ubuntu-latest)	50s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 10s
checks / test (3.12, locked, windows-latest)	3m 24s
checks / test (3.13, lowest-direct, windows-latest)	2m 26s
checks / test (3.10, lowest-direct, ubuntu-latest)	49s
checks / test (3.11, lowest-direct, ubuntu-latest)	43s
checks / test (3.14, lowest-direct, windows-latest)	3m 4s
checks / test (3.10, lowest-direct, windows-latest)	2m 17s
checks / test (3.13, locked, windows-latest)	2m 43s
all-green	3s
	38m 28s

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