fix: remove redundant types (#3097)

Since murat-dogan/node-datachannel#346
`node-datachannel` returns global types where appropriate so it's
no longer necessary to export the polyfill versions.

Author: achingbrain

packages/transport-webrtc/src/webrtc/index.ts

@@ -1,2 +1 @@
 export { RTCSessionDescription, RTCIceCandidate, RTCPeerConnection } from '@ipshipyard/node-datachannel/polyfill'
-export type { RTCDataChannel, RTCDataChannelEvent } from '@ipshipyard/node-datachannel/polyfill'

packages/transport-webrtc/test/muxer.spec.ts

@@ -5,7 +5,6 @@ import { expect } from 'aegir/chai'
 import pRetry from 'p-retry'
 import { stubInterface } from 'sinon-ts'
 import { DataChannelMuxerFactory } from '../src/muxer.js'
-import type { RTCPeerConnection, RTCDataChannelEvent, RTCDataChannel } from '../src/webrtc/index.js'
 
 describe('muxer', () => {
   it('should delay notification of early streams', async () => {