Set cmake_minimum_required(VERSION 3.25) also in the top level Cmake script

To get rid of the deprecation warning.

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b40e711..5895e6f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.9)
+cmake_minimum_required(VERSION 3.25)
 
 project(D3D12MemoryAllocator VERSION 3.0.0)