Fix since for mpsc_error_conversions

Author: ia0

src/libstd/sync/mpsc/mod.rs

@@ -1625,7 +1625,7 @@ impl<T: Send> error::Error for TrySendError<T> {
     }
 }
 
-#[stable(feature = "mpsc_error_conversions", since = "1.23.0")]
+#[stable(feature = "mpsc_error_conversions", since = "1.24.0")]
 impl<T> From<SendError<T>> for TrySendError<T> {
     fn from(err: SendError<T>) -> TrySendError<T> {
         match err {
@@ -1686,7 +1686,7 @@ impl error::Error for TryRecvError {
     }
 }
 
-#[stable(feature = "mpsc_error_conversions", since = "1.23.0")]
+#[stable(feature = "mpsc_error_conversions", since = "1.24.0")]
 impl From<RecvError> for TryRecvError {
     fn from(err: RecvError) -> TryRecvError {
         match err {
@@ -1727,7 +1727,7 @@ impl error::Error for RecvTimeoutError {
     }
 }
 
-#[stable(feature = "mpsc_error_conversions", since = "1.23.0")]
+#[stable(feature = "mpsc_error_conversions", since = "1.24.0")]
 impl From<RecvError> for RecvTimeoutError {
     fn from(err: RecvError) -> RecvTimeoutError {
         match err {