fix: explicitly mark type imports and exports (#540)

Author: wolfy1339

src/paginating-endpoints.ts

@@ -1,5 +1,5 @@
 import {
-  PaginatingEndpoints,
+  type PaginatingEndpoints,
   paginatingEndpoints,
 } from "./generated/paginating-endpoints";
 

src/types.ts

@@ -1,17 +1,17 @@
 import { Octokit } from "@octokit/core";
 import * as OctokitTypes from "@octokit/types";
 
-export {
+export type {
   EndpointOptions,
   RequestInterface,
   OctokitResponse,
   RequestParameters,
   Route,
 } from "@octokit/types";
 
-export { PaginatingEndpoints } from "./generated/paginating-endpoints";
+export type { PaginatingEndpoints } from "./generated/paginating-endpoints";
 
-import { PaginatingEndpoints } from "./generated/paginating-endpoints";
+import type { PaginatingEndpoints } from "./generated/paginating-endpoints";
 
 // // https://stackoverflow.com/a/52991061/206879
 // type RequiredKeys<T> = {