feat: package is now ESM (#661)

BREAKING CHANGE: package is now ESM

README.md

@@ -48,8 +48,7 @@ Node
 Install with <code>npm install @octokit/core</code>
 
 ```js
-const { Octokit } = require("@octokit/core");
-// or: import { Octokit } from "@octokit/core";
+import { Octokit } from "@octokit/core";
 ```
 
 </td></tr>
@@ -342,8 +341,9 @@ This is useful if you build reusable [plugins](#plugins).
 If you would like to make the log level configurable using an environment variable or external option, we recommend the [console-log-level](https://github.com/watson/console-log-level) package. Example
 
 ```js
+import consoleLogLevel from "console-log-level";
 const octokit = new Octokit({
-  log: require("console-log-level")({ level: "info" }),
+  log: consoleLogLevel({ level: "info" }),
 });
 ```
 
@@ -386,18 +386,20 @@ In order to extend `octokit`'s API, the plugin must return an object with the ne
 
 ```js
 // index.js
-const { Octokit } = require("@octokit/core")
+import { Octokit } from "@octokit/core";
+import myPlugin from "./lib/my-plugin.js";
+import octokitPluginExample from "octokit-plugin-example";
 const MyOctokit = Octokit.plugin(
-  require("./lib/my-plugin"),
-  require("octokit-plugin-example")
+  myPlugin,
+  octokitPluginExample
 );
 
 const octokit = new MyOctokit({ greeting: "Moin moin" });
 octokit.helloWorld(); // logs "Moin moin, world!"
 octokit.request("GET /"); // logs "GET / - 200 in 123ms"
 
 // lib/my-plugin.js
-module.exports = (octokit, options = { greeting: "Hello" }) => {
+const plugin = (octokit, options = { greeting: "Hello" }) => {
   // hook into the request lifecycle
   octokit.hook.wrap("request", async (request, options) => {
     const time = Date.now();
@@ -414,18 +416,23 @@ module.exports = (octokit, options = { greeting: "Hello" }) => {
     helloWorld: () => console.log(`${options.greeting}, world!`);
   }
 };
+export default plugin;
 ```
 
 ## Build your own Octokit with Plugins and Defaults
 
 You can build your own Octokit class with preset default options and plugins. In fact, this is mostly how the `@octokit/<context>` modules work, such as [`@octokit/action`](https://github.com/octokit/action.js):
 
 ```js
-const { Octokit } = require("@octokit/core");
+import { Octokit } from "@octokit/core";
+import { paginateRest } from "@octokit/plugin-paginate-rest";
+import { throttling } from "@octokit/plugin-throttling";
+import { retry } from "@octokit/plugin-retry";
+import { createActionAuth } from "@octokit/auth-action";
 const MyActionOctokit = Octokit.plugin(
-  require("@octokit/plugin-paginate-rest").paginateRest,
-  require("@octokit/plugin-throttling").throttling,
-  require("@octokit/plugin-retry").retry,
+  paginateRest,
+  throttling,
+  retry,
 ).defaults({
   throttle: {
     onAbuseLimit: (retryAfter, options) => {
@@ -435,7 +442,7 @@ const MyActionOctokit = Octokit.plugin(
       /* ... */
     },
   },
-  authStrategy: require("@octokit/auth-action").createActionAuth,
+  authStrategy: createActionAuth,
   userAgent: `my-octokit-action/v1.2.3`,
 });