fix(letter): Fix beta/nightly CI
@@ -18,8 +18,6 @@ extern crate native_tls;
#[cfg(feature = "file-transport")]
extern crate serde_json;
#[cfg(feature = "serde-impls")]
-extern crate serde;
-#[cfg(feature = "serde-impls")]
#[macro_use]
extern crate serde_derive;
