Use same width for seconds and milliseconds

src/hyperfine/format.rs

@@ -19,7 +19,7 @@ pub fn format_duration_unit(duration: Second, unit: Option<Unit>) -> (String, Un
     if (duration < 1.0 && unit.is_none()) || unit == Some(Unit::MilliSecond) {
         (format!("{:5.1} ms", duration * 1e3), Unit::MilliSecond)
     } else {
-        (format!("{:5.3} s", duration), Unit::Second)
+        (format!("{:6.3} s", duration), Unit::Second)
     }
 }