multi: add timeout to reply.get

It is possible for this call to hang, like the other calls in this function. Passing through the timeout removes that possibility

src/execnet/multi.py

@@ -307,7 +307,7 @@ def termkill(termfunc, killfunc):
         reply = workerpool.spawn(termkill, termfunc, killfunc)
         replylist.append(reply)
     for reply in replylist:
-        reply.get()
+        reply.get(timeout=timeout)
     workerpool.waitall(timeout=timeout)