message: download: fix "Downloaded 1 crates" message (crates -> crate)
diff: @@ -945,9 +945,16 @@ impl<'a, 'cfg> Drop for Downloads<'a, 'cfg> {
  if !self.success {
  return;
  }
  + // pick the correct plural of crate(s)
  + let crate_string = if self.downloads_finished == 1 {
  + "crate"
  + } else {
  + "crates"
  + };
  let mut status = format!(
  - "{} crates ({}) in {}",
  + "{} {} ({}) in {}",
  self.downloads_finished,
  + crate_string,
  ByteSize(self.downloaded_bytes),
  util::elapsed(self.start.elapsed())
  );
  