fix(typescript): mark import of @octokit/request-error as type (#437)

Author: wolfy1339

src/index.ts

@@ -1,5 +1,5 @@
 import { Octokit } from "@octokit/core";
-import { RequestError } from "@octokit/request-error";
+import type { RequestError } from "@octokit/request-error";
 
 import { errorRequest } from "./error-request";
 import { wrapRequest } from "./wrap-request";