Allow use of orjson instead of json

The difference in speed seems negligible at start up, which is when
most time is taken for actually parsing JSON. I could potentially be
missing something but profiling didn't point to any discernable
difference.

discord/http.py

@@ -99,7 +99,7 @@ async def json_or_text(response: aiohttp.ClientResponse) -> Union[Dict[str, Any]
     text = await response.text(encoding='utf-8')
     try:
         if response.headers['content-type'] == 'application/json':
-            return json.loads(text)
+            return utils.from_json(text)
     except KeyError:
         # Thanks Cloudflare
         pass