Fix more clippy warnings

Author: sylvestre

src/config.rs

@@ -71,7 +71,7 @@ fn default_toolchain_cache_size() -> u64 {
 
 struct StringOrU64Visitor;
 
-impl<'de> de::Visitor<'de> for StringOrU64Visitor {
+impl de::Visitor<'_> for StringOrU64Visitor {
     type Value = u64;
 
     fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {

src/util.rs

@@ -992,7 +992,7 @@ pub fn ascii_unescape_default(s: &[u8]) -> std::io::Result<Vec<u8>> {
                             "incomplete hex escape",
                         ));
                     }
-                    let v = unhex(s[offset])? << 4 | unhex(s[offset + 1])?;
+                    let v = (unhex(s[offset])? << 4) | unhex(s[offset + 1])?;
                     out.push(v);
                     offset += 1;
                 }