Refine flat config types

[Logicer16]

See https://github.com/ota-meshi/eslint-plugin-toml/pull/204

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 80ab192f1543198083dbeb9aa5e3fe471cb1a5b3

The changes in this PR will be included in the next version bump.

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| Name | Type | | ------------------- | ----- | | eslint-plugin-jsonc | Minor |

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[alecmev]

Thanks!