`PackageJsonStandard.engines` should use `LiteralUnion` to improve IDE autocomplete

[oliveryasuna]

https://github.com/sindresorhus/type-fest/blob/main/source/package-json.d.ts#L508

Change to:

		engines?: {
			[EngineName in LiteralUnion<'npm' | 'node', string>]?: string;
		};

The contribution file only mentions new types, so not sure how to proceed. Happy to open a PR myself; just let me know.

[benzaria]

@oliveryasuna

the current type is this:

engines?: {
	[EngineName in 'npm' | 'node' | string]?: string;
};

which makes no diff than

engines?: Record<string, string>;

the union has no effect, so ur LiteralUnion suggestion is better. u can open a PR for that matter.