build: we don't need this field

as we're providing frontend modules even only

Author: mfranzke

package.json

@@ -3,7 +3,6 @@
   "version": "0.1.0",
   "description": "Fast and lightweight dependency-free vanilla JavaScript polyfill for native lazy loading / the awesome loading='lazy'-attribute supported by a Service Worker.",
   "source": "./src/loading-attribute-polyfill.js",
-  "main": "./dist/loading-attribute-polyfill.js",
   "esmodule": "./dist/loading-attribute-polyfill.modern.js",
   "module": "./dist/loading-attribute-polyfill.module.js",
   "umd:main": "./dist/loading-attribute-polyfill.umd.js",