upgrade https-proxy-agent.d.ts

Author: nonoroazoro

src/typings/https-proxy-agent.d.ts

@@ -1,2 +1,14 @@
-// See https://stackoverflow.com/questions/41462729/typescript-react-could-not-find-a-declaration-file-for-module-react-material/41631658#41631658
-declare module "https-proxy-agent";
+// See https://stackoverflow.com/questions/44058101/typescript-declare-third-party-modules#44060120
+declare module "https-proxy-agent"
+{
+    import { Agent } from "http";
+
+    class HttpsProxyAgent extends Agent
+    {
+        constructor(proxy: string);
+    }
+
+    namespace HttpsProxyAgent { }
+
+    export = HttpsProxyAgent;
+}