feat: v3 (#2456)

BREAKING CHANGE: Drop support for NodeJS v14, v16
BREAKING CHANGE: Remove previews support for the REST API
BREAKING CHANGE: remove `agent` option from `octokit.request()`
BREAKING CHANGE: Replace support for Node.js http(s) Agents with documentation on using fetch dispatchers instead (via `@octokit/request`)
BREAKING CHANGE: Remove ability to pass custom request options, except for `method`, `headers`, `body`, `signal` (via @octokit/request)

---------

Co-authored-by: Nick Floyd <139819+nickfloyd@users.noreply.github.com>

.github/workflows/test.yml

@@ -13,9 +13,8 @@ jobs:
     strategy:
       matrix:
         node_version:
-          - 14
-          - 16
           - 18
+          - 20
     steps:
       - uses: actions/checkout@v3
       - name: Use Node.js ${{ matrix.node_version }}

README.md

@@ -22,7 +22,7 @@ The `octokit` package integrates the three main Octokit libraries
     - [`octokit.rest` endpoint methods](#octokitrest-endpoint-methods)
     - [`octokit.request()`](#octokitrequest)
     - [Pagination](#pagination)
-    - [Media Type previews and formats](#media-type-previews-and-formats)
+    - [Media Type formats](#media-type-formats)
     - [Request error handling](#request-error-handling)
   - [GraphQL API queries](#graphql-api-queries)
     - [Schema previews](#schema-previews)
@@ -515,11 +515,9 @@ const issues = await octokit.paginate(octokit.rest.issues.listForRepo, {
 });
 ```
 
-#### Media Type previews and formats
+#### Media Type formats
 
-**Note**: The concept of _preview headers_ has been deprecated from REST API endpoints hosted via `api.github.com` but it still exists in GHES (GitHub Enterprise Server) version 3.2 and below. Instead of using _preview headers_ going forward, new features are now being tested using beta previews that users will have to opt-in to.
-
-Media type previews and formats can be set using `mediaType: { format, previews }` on every request. Required API previews are set automatically on the respective REST API endpoint methods.
+Media type formats can be set using `mediaType: { format }` on every request.
 
 Example: retrieve the raw content of a `package.json` file
 
@@ -535,20 +533,7 @@ const { data } = await octokit.rest.repos.getContent({
 console.log("package name: %s", JSON.parse(data).name);
 ```
 
-Example: retrieve a repository with topics
-
-```js
-const { data } = await octokit.rest.repos.getContent({
-  mediaType: {
-    previews: ["mercy"],
-  },
-  owner: "octocat",
-  repo: "hello-world",
-});
-console.log("topics on octocat/hello-world: %j", data.topics);
-```
-
-Learn more about [Media type formats](https://docs.github.com/en/rest/overview/media-types) and [previews](https://docs.github.com/en/enterprise-server@3.2/rest/overview/api-previews) used on GitHub Enterprise Server.
+Learn more about [Media type formats](https://docs.github.com/en/rest/overview/media-types).
 
 #### Request error handling