chore(deps): bump rstest from 0.19.0 to 0.21.0

Bumps [rstest](https://github.com/la10736/rstest) from 0.19.0 to 0.21.0.
- [Release notes](https://github.com/la10736/rstest/releases)
- [Changelog](https://github.com/la10736/rstest/blob/master/CHANGELOG.md)
- [Commits](la10736/rstest@v0.19.0...v0.21.0)

---
updated-dependencies:
- dependency-name: rstest
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

x509-cert/Cargo.toml

@@ -33,7 +33,7 @@ rand = "0.8.5"
 rsa = { version = "=0.10.0-pre.1", features = ["sha2"] }
 ecdsa = { version = "=0.17.0-pre.5", features = ["digest", "pem"] }
 p256 = "=0.14.0-pre.0"
-rstest = "0.19"
+rstest = "0.21"
 sha2 = { version = "=0.11.0-pre.3", features = ["oid"] }
 tempfile = "3.5.0"
 tokio = { version = "1.38.0", features = ["macros", "rt"] }