Update duration-str requirement in the cargo-minor-patch group

Updates the requirements on [duration-str](https://github.com/baoyachi/duration-str) to permit the latest version.

Updates `duration-str` to 0.21.0
- [Release notes](https://github.com/baoyachi/duration-str/releases)
- [Commits](baoyachi/duration-str@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: duration-str
  dependency-version: 0.21.0
  dependency-type: direct:production
  dependency-group: cargo-minor-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Cargo.toml

@@ -41,7 +41,7 @@ futures = "0.3.29"
 futures-time = "3.0.0"
 url = "2.4.1"
 log = "0.4.20"
-duration-str = "0.20"
+duration-str = "0.21"
 async-broadcast = "0.7.1"
 tokio = { version = "1.49.0", features = ["macros", "net", "rt-multi-thread", "time"], optional = true }
 tokio-util = { version = "0.7.10", features = ["compat"], optional = true }