chore(header): allow deprecated AsciiExt usage

Author: seanmonstar

src/header/common/link.rs

@@ -1,7 +1,7 @@
 use std::fmt;
 use std::borrow::Cow;
 use std::str::FromStr;
-#[allow(unused)]
+#[allow(unused, deprecated)]
 use std::ascii::AsciiExt;
 
 use mime::Mime;

src/header/common/pragma.rs

@@ -1,5 +1,5 @@
 use std::fmt;
-#[allow(unused)]
+#[allow(unused, deprecated)]
 use std::ascii::AsciiExt;
 
 use header::{Header, Raw, parsing};

src/header/common/referrer_policy.rs

@@ -1,5 +1,5 @@
 use std::fmt;
-#[allow(unused)]
+#[allow(unused, deprecated)]
 use std::ascii::AsciiExt;
 
 use header::{Header, Raw, parsing};

src/header/shared/charset.rs

@@ -1,6 +1,6 @@
 use std::fmt::{self, Display};
 use std::str::FromStr;
-#[allow(unused)]
+#[allow(unused, deprecated)]
 use std::ascii::AsciiExt;
 
 use self::Charset::*;

src/header/shared/quality_item.rs

@@ -1,4 +1,4 @@
-#[allow(unused)]
+#[allow(unused, deprecated)]
 use std::ascii::AsciiExt;
 use std::cmp;
 use std::default::Default;