chore: address clippy warnings

actix-http/src/header/map.rs

@@ -830,7 +830,7 @@ impl<'a> Drain<'a> {
     }
 }
 
-impl<'a> Iterator for Drain<'a> {
+impl Iterator for Drain<'_> {
     type Item = (Option<HeaderName>, HeaderValue);
 
     fn next(&mut self) -> Option<Self::Item> {

actix-http/src/helpers.rs

@@ -61,7 +61,7 @@ pub fn write_content_length<B: BufMut>(n: u64, buf: &mut B, camel_case: bool) {
 /// perform a remaining length check before writing.
 pub(crate) struct MutWriter<'a, B>(pub(crate) &'a mut B);
 
-impl<'a, B> io::Write for MutWriter<'a, B>
+impl<B> io::Write for MutWriter<'_, B>
 where
     B: BufMut,
 {

actix-http/src/http_message.rs

@@ -103,7 +103,7 @@ pub trait HttpMessage: Sized {
     }
 }
 
-impl<'a, T> HttpMessage for &'a mut T
+impl<T> HttpMessage for &mut T
 where
     T: HttpMessage,
 {