build: rename "typings" → "types"

package.json

@@ -5,7 +5,7 @@
   "description": "An optimised way to copy'ing an object. A small and simple integration",
   "main": "dist/index.cjs.js",
   "module": "dist/index.esm.js",
-  "typings": "types/index.d.ts",
+  "types": "types/index.d.ts",
   "scripts": {
     "test": "ava",
     "lint": "eslint . --ext .js,.jsx,.ts,.tsx",