ipfs: add buffer for better batching

ipfs/provide.go

@@ -106,7 +106,7 @@ func (r *Reprovider) Run(ctx context.Context, interval, timeout time.Duration, b
  // include a slight buffer for CIDs that are about to expire
  // so they will be provided as one batch
  buffer := interval / 10
- minAnnouncement := time.Now().Add(-interval).Add(buffer)
+ minAnnouncement := time.Now().Add(-(interval - buffer))
  for _, c := range cids {
  // only provide CIDs that have not been provided within the
  // last interval