fix: prevent unclosed client session / unclosed connector (#2618)

Takes inspiration from Rapptz/discord.py#1967
Fixes #2399

discord/client.py

@@ -714,6 +714,7 @@ async def close(self) -> None:
         if self._closed:
             return
 
+        await self.http.close()
         self._closed = True
 
         for voice in self.voice_clients:
@@ -726,7 +727,6 @@ async def close(self) -> None:
         if self.ws is not None and self.ws.open:
             await self.ws.close(code=1000)
 
-        await self.http.close()
         self._ready.clear()
 
     def clear(self) -> None: