Use a range for CMake minimum versions, 3.2...3.12: support CMake 4.0

[musicinmybrain]

CMake 4.0 drops support for CMake <3.5, so minimum versions need to be adjusted for forward compatibility. As long as we are touching the minimum version, let’s advance to 3.12, which can be considered the oldest “modern” CMake release, and which is available in all known supported Linux distributions today.

[mrgreywater]

Thanks for the heads up. But since we don't need any newer features, I think we should only advance to 3.5 if that's what cmake still supports. Also the README.md would probably need a small update for the required cmake version.

[musicinmybrain]

Thanks for the heads up. But since we don't need any newer features, I think we should only advance to 3.5 if that's what cmake still supports. Also the README.md would probably need a small update for the required cmake version.

Ok, adjusted on both counts and force-pushed.

Looking back at CMakeLists.txt, there are a couple of workarounds that you could dispense with if you did choose to update the minimum version to 3.12:

earcut.hpp/CMakeLists.txt

Lines 27 to 30 in 7fa7aa3

	if("${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}" GREATER 3.7)
	# Allow C++11 requirements to propagate when using recent CMake versions
	target_compile_features(earcut_hpp INTERFACE cxx_std_11)
	endif()

earcut.hpp/CMakeLists.txt

Lines 37 to 40 in 7fa7aa3

	# In CMake 3.12, use target_link_libraries(fixtures PUBLIC earcut_hpp libtess2).
	# Since we support down to CMake 3.2, we need to manually propagate usage requirements of earcut_hpp
	target_include_directories(fixtures PRIVATE "$<TARGET_PROPERTY:earcut_hpp,INTERFACE_INCLUDE_DIRECTORIES>")
	target_compile_features(fixtures PRIVATE "$<TARGET_PROPERTY:earcut_hpp,INTERFACE_COMPILE_FEATURES>")

[musicinmybrain]

I’m going to update this again to set a minimum version range, 3.2...3.12. That way, CMake 3.2 will still work (as before this PR), if anyone is still using it, but CMake releases that can’t support such old policy versions (e.g., CMake 4.0 can’t support CMake<3.5, and CMake<3.10 is already deprecated) can still work with a higher minimum version.