递归的 `--config-path` 不会递归

        --config-path [Path for the configuration file]
                        Recursively searches the given path for the
                        rustfmt.toml config file. If not found reverts to the
                        input file path

$ rustfmt --config-path ~/Downloads/test_issue/my_crate/src/main.rs --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
Could not parse TOML: expected an equals, found an identifier at line 1 column 4
$ rustfmt --config-path ~/Downloads/test_issue/my_crate/src/ --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
Error: unable to find a config file for the given path: `~/Downloads/test_issue/my_crate/src/`
$ rustfmt --config-path ~/Downloads/test_issue/my_crate/src --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
Error: unable to find a config file for the given path: `~/Downloads/test_issue/my_crate/src`
$ rustfmt --config-path ~/Downloads/test_issue/my_crate --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
fn fjsdlkfjklsdajflksdjlfdasdsadsadsaadkjdskljflkasj_jflksjdklfjsdlkjflkdjslkfjas(a: i32, b: i32, c: i32) {
    println!("TEST");
}

fn main() {
    fjsdlkfjklsdajflksdjlfdasdsadsadsaadkjdskljflkasj_jflksjdklfjsdlkjflkdjslkfjas(1, 2, 3);
    println!("Hello, world!");
}
$ rustfmt --config-path ~/Downloads/test_issue/ --edition 2018 < ~/Downloads/test_issue/my_crate/src/main.rs
Error: unable to find a config file for the given path: `~/Downloads/test_issue/`
**重现**

测试项目来自 https://GitHub.com/Rust-analyzer/Rust-analyzer/issues/6973#issuecomment-762881775