Replace deprecated crates

[qryxip]

• dirs
• tempdir

Crate:  dirs
Title:  dirs is unmaintained, use dirs-next instead
Date:   2020-10-16
URL:    https://rustsec.org/advisories/RUSTSEC-2020-0053
Dependency tree:
dirs 3.0.1
└── cargo-atcoder 0.3.1-alpha.0

Crate:  tempdir
Title:  `tempdir` crate has been deprecated; use `tempfile` instead
Date:   2018-02-13
URL:    https://rustsec.org/advisories/RUSTSEC-2018-0017
Dependency tree:
tempdir 0.3.7
└── cargo-atcoder 0.3.1-alpha.0