fix properly import webrtc-adapter

lib/adapter.ts

@@ -1,4 +1,4 @@
-import "webrtc-adapter";
+import { adapter as _ } from "webrtc-adapter";
 
 export const RTCSessionDescription =
   // @ts-ignore

test/faker.ts

@@ -1,5 +1,5 @@
 import { WebSocket } from 'mock-socket';
-import "webrtc-adapter";
+import { adapter as _ } from 'webrtc-adapter';
 
 const fakeGlobals = {
     WebSocket,