fix(typescript): properly import the TransformStream type

When compiling with TypeScript with module set to "node16" and
moduleResolution to "node16", the following error would be thrown:

> node_modules/engine.io-parser/build/cjs/index.d.ts:6:54 - error TS2304: Cannot find name 'TransformStream'.
> 6 export declare function createPacketEncoderStream(): TransformStream<Packet, any>;
>                                                        ~~~~~~~~~~~~~~~
> node_modules/engine.io-parser/build/cjs/index.d.ts:7:96 - error TS2304: Cannot find name 'TransformStream'.
> 7 export declare function createPacketDecoderStream(maxPayload: number, binaryType: BinaryType): TransformStream<Uint8Array, any>;
>                                                                                                  ~~~~~~~~~~~~~~~
> Found 2 errors in the same file, starting at: node_modules/engine.io-parser/build/cjs/index.d.ts:6

This is because the TransformStream object is not exposed in the global
scope in the `@types/node` package, even though it is since Node.js
`v18.0.0`.

Reference: https://nodejs.org/api/webstreams.html#class-transformstream

Note: we only import the TransformStream type (not value) because it
isn't defined on older Node.js versions.

Related:

- https://github.com/socketio/engine.io-parser/issues/136
- socketio/socket.io-client#1606

Author: darrachequesne

lib/index.ts

@@ -7,6 +7,9 @@ import {
   BinaryType,
   ERROR_PACKET,
 } from "./commons.js";
+// we can't import TransformStream as a value because it was added in Node.js v16.5.0, so it would break on older Node.js versions
+// reference: https://nodejs.org/api/webstreams.html#class-transformstream
+import type { TransformStream } from "node:stream/web";
 
 const SEPARATOR = String.fromCharCode(30); // see https://en.wikipedia.org/wiki/Delimiter#ASCII_delimited_text
 
@@ -47,6 +50,7 @@ const decodePayload = (
 };
 
 export function createPacketEncoderStream() {
+  // @ts-expect-error
   return new TransformStream({
     transform(packet: Packet, controller) {
       encodePacketToBinary(packet, (encodedPacket) => {
@@ -122,6 +126,7 @@ export function createPacketDecoderStream(
   let expectedLength = -1;
   let isBinary = false;
 
+  // @ts-expect-error
   return new TransformStream({
     transform(chunk: Uint8Array, controller) {
       chunks.push(chunk);