CORS test sends non-CORS request

There's a [test](https://github.com/ipfs/gateway-conformance/blob/d855ec4fb9dac4a5aaecf3776037b005cc74c566/tests/path_gateway_cors_test.go#L18-L34):

> "GET Responses from Gateway should include CORS headers allowing JS from other origins to read the data cross-origin."

It makes a GET request to `"/ipfs/{{CID}}/"` and expects `Access-Control-Allow-Origin` etc in the response.

The test sends:

```
GET /ipfs/bafkqabtimvwgy3yk/ HTTP/1.1
Host: host.docker.internal:8080
User-Agent: Go-http-client/1.1
Accept-Encoding: gzip
```

The fetch spec [says](https://fetch.spec.whatwg.org/#http-requests):

> A CORS request is an HTTP request that includes an [Origin](https://fetch.spec.whatwg.org/#http-origin) header. It cannot be reliably identified as participating in the [CORS protocol](https://fetch.spec.whatwg.org/#cors-protocol) as the [Origin](https://fetch.spec.whatwg.org/#http-origin) header is also included for all [requests](https://fetch.spec.whatwg.org/#concept-request) whose [method](https://fetch.spec.whatwg.org/#concept-request-method) is neither `GET` nor `HEAD`.

There is no `Origin` header in the request, so this is not a CORS request.

Why does the test expect CORS headers in the response?