Compile failure with Cmake 4.0 due cmake_minimum_required <3.5 support removed

[oyvindln]

Due to this upstream change, fftw3 will not compile with cmake 4.0 - with the error:

Error:   Compatibility with CMake < 3.5 has been removed from CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

  Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.

It seems it can be fixed either by just bumping the minimum to 3.5 (which is 10 years old now and cmake is not the primary build system anyhow), or min..max syntax.

See also this note from fedora linux about the cmake change. Not sure if any linux distros use cmake instead of autoconf to build, though it is at least used by vcpkg which is where I encountered it.