https://blog.csdn.net/juluwangriyue/article/details/119952166
https://www.cnblogs.com/pandamohist/p/13699911.html
# fetchcontent重点来了
#-------------------------------------------------------------------
include(fetchcontent)
fetchcontent_declare( spdlog #库名字
GIT_REPOSITORY https://gitee.com/mohistH/spdlog.git # 仓库地址
GIT_TAG v1.x # 库版本
SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/ext/spdlog # 指定库下载地址
)
fetchcontent_makeavailable(spdlog)