Fix `is_jsonable` if integer key in dict #7299

Job	Run time
build-windows (3.8)	6m 20s
build-ubuntu (3.8, Repository only)	1m 34s
build-ubuntu (3.8, Everything else)	4m 17s
build-ubuntu (3.13, Repository only)	1m 35s
build-ubuntu (3.13, Everything else)	4m 0s
build-ubuntu (3.13, lfs)	47s
build-ubuntu (3.8, fastai)	1m 22s
build-ubuntu (3.10, fastai)	59s
build-ubuntu (3.8, tensorflow)	1m 5s
build-ubuntu (3.10, tensorflow)	57s
build-ubuntu (3.8, Python 3.8, torch_1.11)	1m 24s
build-ubuntu (3.12, torch_latest)	1m 4s
	25m 24s

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