Update cron requirement from 0.14.0 to 0.15.0 (#92)

Updates the requirements on [cron](https://github.com/zslayton/cron) to permit the latest version.
- [Release notes](https://github.com/zslayton/cron/releases)
- [Commits](zslayton/cron@v0.14.0...v0.14.0)

---
updated-dependencies:
- dependency-name: cron
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Cargo.toml

@@ -38,7 +38,7 @@ bolero = { version = "0.12.0", features = ["arbitrary"] }
 bytes = "1.9"
 chrono = "0.4.31"
 console_error_panic_hook = "0.1.7"
-cron = "0.14.0"
+cron = "0.15.0"
 deepsize = "0.2.0"
 educe = "0.6.0"
 futures = "0.3.29"