refactor(multiple): Clippy run

src/header/shared/charset.rs

@@ -91,7 +91,7 @@ impl Charset {
             Gb2312 => "GB2312",
             Big5 => "5",
             Koi8_R => "KOI8-R",
-            Ext(ref s) => &s
+            Ext(ref s) => s
         }
     }
 }

src/header/shared/entity.rs

@@ -4,10 +4,10 @@ use std::fmt::{self, Display};
 // check that each char in the slice is either:
 // 1. %x21, or
 // 2. in the range %x23 to %x7E, or
-// 3. in the range %x80 to %xFF
+// 3. above %x80
 fn check_slice_validity(slice: &str) -> bool {
     slice.bytes().all(|c|
-        c == b'\x21' || (c >= b'\x23' && c <= b'\x7e') | (c >= b'\x80' && c <= b'\xff'))
+        c == b'\x21' || (c >= b'\x23' && c <= b'\x7e') | (c >= b'\x80'))
 }
 
 /// An entity tag, defined in [RFC7232](https://tools.ietf.org/html/rfc7232#section-2.3)