Recommend upgrade to CPM v0.40.1 or newer to address FetchContent_Populate deprecation

[dksmiffs]

When configuring CMake for KDIS using CMake 3.30 or newer, the following warning is posted:

CMake Warning (dev) at <ParentPath>/CMake/v3.30.3/share/cmake-3.30/Modules/FetchContent.cmake:1953 (message):
  Calling FetchContent_Populate(googletest) is deprecated, call
  FetchContent_MakeAvailable(googletest) instead.  Policy CMP0169 can be set
  to OLD to allow FetchContent_Populate(googletest) to be called directly for
  now, but the ability to call it with declared details will be removed
  completely in a future version.
Call Stack (most recent call first):
  cmake/CPM.cmake:1004 (FetchContent_Populate)
  cmake/CPM.cmake:798 (cpm_fetch_package)
  tests/CMakeLists.txt:24 (CPMAddPackage)
This warning is for project developers.  Use -Wno-dev to suppress it.

This issue was corrected upstream here. Recommend that KDIS move to a more modern version of CPM.