Fix more deprecation warnings

discord/utils.py

@@ -328,7 +328,10 @@ async def async_all(gen, *, check=_isawaitable):
     return True
 
 async def sane_wait_for(futures, *, timeout):
-    done, pending = await asyncio.wait(futures, timeout=timeout, return_when=asyncio.ALL_COMPLETED)
+    ensured = [
+        asyncio.ensure_future(fut) for fut in futures
+    ]
+    done, pending = await asyncio.wait(ensured, timeout=timeout, return_when=asyncio.ALL_COMPLETED)
 
     if len(pending) != 0:
         raise asyncio.TimeoutError()