[conan center] advice set_property rather set_target_properties

[SSE4]

from https://github.com/conan-io/conan-center-index/pull/1254#discussion_r403488929 /cc @uilianries for CMakeLists.txt and test_package/CMakeLists.txt, we may advice set_property over set_target_properties for advanced CMake compatibility

[Croydon]

If you are going to implement this, then I would say this should be just a warning, not an error

[uilianries]

Yes, also, set_target_properties is okay when the required version is CMake 3+ (and really need Cmake 3)