add missing packageManager field

Author: dcousens

package.json

@@ -4,6 +4,7 @@
   "version": "1.0.1",
   "description": "A small Javascript utility to determine a Typescript type from an ndjson stream",
   "main": "cli.ts",
+  "packageManager": "[email protected]",
   "scripts": {
     "test": "node test/index.ts"
   },