Update utf8.rs

Author: chris-ha458

regex-automata/src/util/utf8.rs

@@ -99,18 +99,13 @@ pub(crate) fn decode_last(bytes: &[u8]) -> Option<Result<char, u8>> {
 /// `None`.
 #[cfg_attr(feature = "perf-inline", inline(always))]
 fn len(byte: u8) -> Option<usize> {
-    if byte <= 0x7F {
-        return Some(1);
-    } else if byte & 0b1100_0000 == 0b1000_0000 {
-        return None;
-    } else if byte <= 0b1101_1111 {
-        Some(2)
-    } else if byte <= 0b1110_1111 {
-        Some(3)
-    } else if byte <= 0b1111_0111 {
-        Some(4)
-    } else {
-        None
+    match byte {
+        0b0000_0000..=0b0111_1111 => Some(1),
+        0b1000_0000..=0b1011_1111 => None,
+        0b1100_0000..=0b1101_1111 => Some(2),
+        0b1110_0000..=0b1110_1111 => Some(3),
+        0b1111_0000..=0b1111_0111 => Some(4),
+        _ => None,
     }
 }