chore: add format script

Author: jamesgeorge007

package-lock.json

@@ -7,13 +7,15 @@
   "author": "James George",
   "license": "MIT",
   "scripts": {
+    "format": "prettier --write index.js",
     "build": "ncc build index.js -o dist"
   },
   "dependencies": {
     "@actions/core": "^1.2.4",
     "actions-toolkit": "^5.0.0"
   },
   "devDependencies": {
-    "@zeit/ncc": "^0.22.3"
+    "@zeit/ncc": "^0.22.3",
+    "prettier": "^2.0.5"
   }
 }