SDL_mixer: Bump mpg123

From 9a35e1ed9943e1876fa64ad759f3925dde543217 Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Tue, 18 Jul 2023 00:37:47 +0200
Subject: [PATCH] Bump mpg123

---
 .gitmodules     | 2 +-
 external/mpg123 | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.gitmodules b/.gitmodules
index 66d8781e..99ed6ef8 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -25,7 +25,7 @@
 [submodule "external/mpg123"]
 	path = external/mpg123
 	url = https://github.com/libsdl-org/mpg123.git
-	branch = v1.29.3-SDL
+	branch = v1.31.3-SDL
 [submodule "libxmp"]
 	path = external/libxmp
 	url = https://github.com/libsdl-org/libxmp.git
diff --git a/external/mpg123 b/external/mpg123
index 21471781..fcb6775c 160000
--- a/external/mpg123
+++ b/external/mpg123
@@ -1 +1 @@
-Subproject commit 21471781893f9a615b1d6ffeab435955a51214c6
+Subproject commit fcb6775ca019a80289d1b60b968b33784c8b8f16