SDL_image: bump libpng from 1.6.37 to 1.6.40 (3c378)

From 3c37837ae81aa1d717214349f6d63605b781ef41 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Tue, 17 Oct 2023 18:56:50 +0300
Subject: [PATCH] bump libpng from 1.6.37 to 1.6.40

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

diff --git a/.gitmodules b/.gitmodules
index bc9b36ae..33c54371 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -5,7 +5,7 @@
 [submodule "external/libpng"]
 	path = external/libpng
 	url = https://github.com/libsdl-org/libpng.git
-	branch = v1.6.37-SDL
+	branch = v1.6.40-SDL
 [submodule "external/libwebp"]
 	path = external/libwebp
 	url = https://github.com/libsdl-org/libwebp.git
diff --git a/external/libpng b/external/libpng
index 99917305..bab1405b 160000
--- a/external/libpng
+++ b/external/libpng
@@ -1 +1 @@
-Subproject commit 999173059e2651fab2a0102eeba18748c4bd9827
+Subproject commit bab1405bf3c2ac72b0136c54a7b7109eef1f7c10