proto: drop unused From impl

Author: djc

quinn-proto/src/transport_error.rs

@@ -60,17 +60,6 @@ impl fmt::Display for Error {
 
 impl std::error::Error for Error {}
 
-impl From<Code> for Error {
-    fn from(x: Code) -> Self {
-        Self {
-            code: x,
-            frame: None,
-            reason: "".to_string(),
-            crypto: None,
-        }
-    }
-}
-
 /// Transport-level error code
 #[derive(Copy, Clone, Eq, PartialEq)]
 pub struct Code(u64);