Fix Cargo warning on latest Rust versions about custom cfg flags

Author: AlexTMjugador

Cargo.toml

@@ -34,3 +34,6 @@ async = ["futures-core", "futures-io", "tokio", "tokio-util", "bytes", "pin-proj
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(fuzzing)'] }