SDL: Fixed warning, needs more work by @icculus

SDL Commits
1 
From 8acb91936a6f8d96ab1beca976553c0329a1ba10 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Tue, 23 Apr 2024 14:35:55 -0700
Subject: [PATCH] Fixed warning, needs more work by @icculus

---
 src/filesystem/SDL_filesystem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/filesystem/SDL_filesystem.c b/src/filesystem/SDL_filesystem.c
index 65be3e0f4e32a..0f06d7d179453 100644
--- a/src/filesystem/SDL_filesystem.c
+++ b/src/filesystem/SDL_filesystem.c
@@ -154,7 +154,7 @@ static char *CaseFoldUtf8String(const char *fname)
         SDL_assert(num_folded <= SDL_arraysize(folded));
         for (int i = 0; i < num_folded; i++) {
             SDL_assert(written < allocation);
-            retval[written++] = folded[i];
+            retval[written++] = (char)folded[i];
         }
     }