SDL_mixer: update libmpg123 (f3318)

SDL Commits
1 
From f3318efa16ecc2f5a3beec8a004b9cbc4cd38d40 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Fri, 11 Oct 2024 20:10:28 +0300
Subject: [PATCH] update libmpg123

---
 external/mpg123 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/external/mpg123 b/external/mpg123
index 5a0927354..4b68a0f39 160000
--- a/external/mpg123
+++ b/external/mpg123
@@ -1 +1 @@
-Subproject commit 5a09273541050480e84881426e84e619c629baa7
+Subproject commit 4b68a0f398928343eebb89b152da483bc1f250ac