fix: fix typescript nodenext resolution

[rayzr522]

tiny fix here: while your ESModule build is working totally fine, when downstream consumers are set up to use nodenext for their module & moduleResolution settings, typescript reads your package.json and sees that the exports.node points to the src folder and tries to also look there for the typescript typings

as per the typescript docs this just lets typescript know to still keep looking in the dist/src folder for the types :)