adapt cmake minimum version

cmake boost refactor lifted minimum cmake version to 3.25. There was
really no good reason for that specific version except some github
forum entry where I checked for cmake boost examples set it to 3.25.
Our CI currently runs on ubuntu 22.04LTS which comes with cmake 3.22.
Lets see if it passes when lowering the required version to that one.

CMakeLists.txt

@@ -2,7 +2,7 @@
 # Author: Marco Biasini
 #-------------------------------------------------------------------------------
 
-cmake_minimum_required(VERSION 3.25 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.22 FATAL_ERROR)
 
 # Set CMake policies
 # Behaviour of target_link_libraries, always link by full path. CMP0060 can