Replace node-fetch by builtin Node fetch API (#30)

* Replace node-fetch by builtin Node fetch API

* Run npm update

README.md

@@ -46,8 +46,7 @@ in a `.env` file at the repository root.
    `python -m http.server 8080 -d ./out`).
 
 `rollup` is used for browser packing of scripts and copying of static assets. The
-data fetching script is plain JavaScript with `node-fetch` used to polyfill
-`fetch()`-like API.
+data fetching script is plain JavaScript with the Node `fetch` API.
 
 ### Adding a new version
 

build/utils/compose-fetcher.js

@@ -1,5 +1,4 @@
 const fs = require('fs').promises;
-const fetch = require('node-fetch');
 const nodeUtil = require('util');
 const exec = nodeUtil.promisify(require('child_process').exec);
 

package.json

@@ -16,7 +16,6 @@
     "dompurify": "^2.0.7",
     "lit-element": "^2.2.1",
     "marked": "^0.7.0",
-    "node-fetch": "^2.7.0",
     "posthtml": "^0.12.0",
     "rollup": "^1.24.0",
     "rollup-plugin-babel": "^4.3.3",