Upgrade Conan CMake wrapper to the latest version

[Chris Mc]

user-management/backend/cmake/conan-setup.cmake

Line 9 in c861e7d

 file(DOWNLOAD "https://github.com/conan-io/cmake-conan/raw/v0.15/conan.cmake" ${CONAN_WRAPPER}) 

The original work was to overcome a limitation which has now been resolved conan-io/cmake-conan#294 (comment)

https://github.com/conan-io/cmake-conan/releases/tag/v0.16