Function read_all_config_versions 

pub fn read_all_config_versions(dir: &Path) -> Vec<(String, Option<String>)>

读取目录下所有已知配置文件的版本号。

use std::path::Path;
use quanttide_devops::contract::read_all_config_versions;
let versions = read_all_config_versions(Path::new("/tmp/nonexistent"));
assert!(versions.is_empty());