update SessionsNotSupported error message

Author: isabelatkinson

src/error.rs

@@ -302,9 +302,7 @@ pub enum ErrorKind {
     SrvLookupError { message: String },
 
     /// The Client does not support sessions.
-    #[error(
-        display = "Attempted to start a session on a deployment that does not support sessions"
-    )]
+    #[error("Attempted to start a session on a deployment that does not support sessions")]
     SessionsNotSupported,
 
     /// A timeout occurred before a Tokio task could be completed.