SDL_image: update vendored libavif.

From 860a6f1a2e03c54e7bdaf85fc5d9526379bc0c1d Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Thu, 21 May 2026 21:14:50 +0300
Subject: [PATCH] update vendored libavif.

(cherry picked from commit 193874e34cd99bcd17a857f0e60008bce186e594)
---
 external/libavif | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/external/libavif b/external/libavif
index 62cfd085..ee829431 160000
--- a/external/libavif
+++ b/external/libavif
@@ -1 +1 @@
-Subproject commit 62cfd08583e85d77b88b2cb6ccd76ce5fbe46dbf
+Subproject commit ee829431ceaed31a34b7e1420f7f18180e7eae23