Remove incorrect comment

`lower_bound` would only work if there was at
least 1 preexisting stream for the given priority.

It would be possible to inspect the priority value
when unwrapping the option, but I think this would
be more complex that just explicitly specifying
the full range for the priority in question.

quinn-proto/src/connection/streams/mod.rs

@@ -338,8 +338,6 @@ impl<'a> SendStream<'a> {
 /// Push a pending stream ID with the given priority, queued after all preexisting streams for the priority
 fn push_pending(pending: &mut BTreeMap<PendingPriority, StreamId>, id: StreamId, priority: i32) {
     // Get all preexisting streams of this priority
-    // We only actually need the lowest recency value, so this could be implemented more tersely with
-    // `BTreeMap::lower_bound`, but as of writing that API is unfortunately still nightly only
     let mut range = pending.range((
         Bound::Included(PendingPriority {
             priority,