Fixes the dist folder not being in the npm package

The prepare scripts runs after npm i and before publish ensuring the dist folder is present

Author: krazyjakee

package.json

@@ -17,6 +17,7 @@
   "main": "dist/astar.js",
   "types": "dist/astar.d.ts",
   "scripts": {
+    "prepare": "tsc",
     "build": "tsc",
     "run-example": "cd example && yarn install && yarn run dev"
   },