message: Simplify character matching
diff: @@ -22,7 +22,7 @@ const ERR: &[u8] = b"-ERR";
  #[inline]
  fn is_valid_op_char(c: u8) -> bool {
  - (c >= 0x41 && c <= 0x5A) || c == '-' as u8 || c == '+' as u8
  + (c >= 0x41 && c <= 0x5A) || c == b'-' || c == b'+'
  }
  pub(crate) struct ReadLoopState {
  