Update BUILDING.md

Co-authored-by: Chengzhong Wu <legendecas@gmail.com>

Author: targos

BUILDING.md

@@ -157,7 +157,7 @@ Depending on the host platform, the selection of toolchains may vary.
 | ---------------- | -------------------------------------------------------------- |
 | Linux            | GCC >= 12.2                                                    |
 | Windows          | Visual Studio >= 2022 with the Windows 10 SDK on a 64-bit host |
-| macOS            | Xcode >= 16.3 (Apple LLVM >= 17)                               |
+| macOS            | Xcode >= 16.3 (Apple LLVM >= 19)                               |
 
 ### Official binary platforms and toolchains