message: Remove unnecessary integer cast
diff: @@ -151,7 +151,7 @@ impl Index {
  bloom_size: bloom_size,
  };
  - write_size(&mut hdr_buf[0..4], bloom_size as u32);
  + write_size(&mut hdr_buf[0..4], bloom_size);
  write_size(&mut hdr_buf[4..8], 0);
  // write fanout to hdr_buf
  