Use native tools

src/github.ts

@@ -0,0 +1,12 @@
+import * as httpm from '@actions/http-client';
+
+export interface GitHubRelease {
+  id: number;
+  tag_name: string;
+}
+
+export const getRelease = async (version: string): Promise<GitHubRelease | null> => {
+  const url: string = `https://github.com/upx/upx/releases/${version !== 'latest' ? `v${version}` : version}`;
+  const http: httpm.HttpClient = new httpm.HttpClient('ghaction-upx');
+  return (await http.getJson<GitHubRelease>(url)).result;
+};