message: Make CSV writer inflexible bc of const row count
diff: @@ -43,7 +43,6 @@ impl Measurements {
  let block_store = block_store.lock().unwrap();
  let mut wtr = csv::WriterBuilder::new()
  .terminator(csv::Terminator::CRLF)
  - .flexible(true)
  .from_writer(sink);
  // Header row
  