Fix CMake deprecation warnings in libsamplerate

Author: tuxu

CMakeLists.txt

@@ -1,7 +1,7 @@
 # https://stackoverflow.com/questions/51907755/building-a-pybind11-module-with-cpp-and-cuda-sources-using-cmake
 
 cmake_minimum_required(VERSION 3.15)
-set(CMAKE_POLICY_VERSION_MINIMUM 3.5)
+set(CMAKE_POLICY_VERSION_MINIMUM 3.15)
 
 project(python-samplerate)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)