Fix warnings

src/hpack/encoder.rs

@@ -44,6 +44,7 @@ impl Encoder {
     /// Queues a max size update.
     ///
     /// The next call to `encode` will include a dynamic size update frame.
+    #[allow(dead_code)]
     pub fn update_max_size(&mut self, val: usize) {
         match self.size_update {
             Some(SizeUpdate::One(old)) => {