fix: Reduce npm package size

Author: hata6502

package.json

@@ -14,6 +14,9 @@
   "license": "MIT",
   "author": "Tomoyuki Hata <hato6502@gmail.com>",
   "main": "dist/index.js",
+  "files": [
+    "dist"
+  ],
   "scripts": {
     "check-license": "license-checker --excludePackages 'css-select@1.2.0;dictionary-en@3.0.0;domutils@1.5.1;optimist@0.6.1;tiny-segmenter@0.2.0;trim@0.0.1;union@0.5.0;unorm@1.6.0;zlibjs@0.2.0' --excludePrivatePackages --onlyAllow 'Apache-2.0;BSD;BSD-2-Clause;BSD-3-Clause;CC0-1.0;CC-BY-3.0;CC-BY-4.0;ISC;MIT;Public Domain;Unlicense;WTFPL' --production --unknown > /dev/null",
     "fix": "prettier --write .",