fix: add package.json to exports (#2026)

Co-authored-by: Philippe de Saint Chamas <philippe.desaintchamas@kili-technology.com>

Author: p-desaintchamas

package.json

@@ -47,6 +47,7 @@
  ],
  "exports": {
  ".": "./index.js",
+ "./package.json": "./package.json",
  "./promise": "./promise.js",
  "./promise.js": "./promise.js"
  },