chore: expose package.json in exports map

[lukeed]

Changes

This is necessary so that consumers can read/parse the package's config.
While it may not be very often that a CLI/bin gets parsed, it will still happen.

For example, Svelte kit is doing this to execute snowpack manually in the background:

require.resolve('snowpack/package.json');

Without this change, all Node 12.x and 14.x users get this error immediately:

Testing

No tests, just removes Node error.

Docs

Bug fix only.

[vercel]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployment, click below or on the icon next to each commit.

🔍 Inspect: https://vercel.com/pikapkg/snowpack/892coakbz
✅ Preview: https://snowpack-git-patch-1.pikapkg.vercel.app

[drwpow]

LGTM! Thanks

[FredKSchott]

bah, I still hate that this is default export map behavior. Thanks for the fix luke!