message: Apply formatting and make the message more user-friendly
diff: @@ -518,7 +518,13 @@ impl reactor::Reactor for Reactor {
  block_header_with_old_version,
  }) => {
  let old_version = block_header_with_old_version.protocol_version();
  - fatal!(effect_builder, "downgrade is not allowed, exiting; current_version={}; old_version={}", current_version, old_version).await;
  + fatal!(
  + effect_builder,
  + "network is still running an older version, exiting; current_version={}; old_version={}",
  + current_version,
  + old_version
  + )
  + .await;
  None
  }
  Err(error) => {
  