message: subscriber: use `Formatter::write_char` rather than `pad`
  This commit replaces uses of `Formatter::pad` with
  `Formatter::write_char` wherever a single character is written to a
  formatter. This prevents us from inadvertantly padding these characters
  incorrectly, and may avoid some overhead.
diff: @@ -516,7 +516,7 @@ where
  })?;
  if seen {
  - f.pad(" ")?;
  + f.write_char(' ')?;
  }
  Ok(())
  }
  @@ -548,13 +548,13 @@ where
  }
  fn bold(&self) -> Style {
  - #[cfg(feature = "ansi")] {
  + #[cfg(feature = "ansi")]
  + {
  if self.ansi {
  return Style::new().bold();
  }
  }
  -
  Style::new()
  }
  }
  @@ -579,11 +579,11 @@ where
  if !fields.is_empty() {
  write!(f, "{}{}{}", bold.paint("{"), fields, bold.paint("}"))?;
  }
  - f.pad(":")
  + f.write_char(':')
  })?;
  if seen {
  - f.pad(" ")?;
  + f.write_char(' ')?;
  }
  Ok(())
  }
  @@ -594,7 +594,9 @@ struct Style;
  #[cfg(not(feature = "ansi"))]
  impl Style {
  - fn new() -> Self { Style }
  + fn new() -> Self {
  + Style
  + }
  fn paint(&self, d: impl fmt::Display) -> impl fmt::Display {
  d
  }
  