[CMAKE] Don't set iwyu and clang-tidy properties on nlohmann_json with cmake <3.19#3568

marcalff merged 2 commits intoopen-telemetry:mainopen-telemetry/opentelemetry-cpp:mainfrom

dbarker:fix_cmake_fetch_nlohmann_jsondbarker/opentelemetry-cpp:fix_cmake_fetch_nlohmann_jsonCopy head branch name to clipboard