Update cron-descriptor requirement

Updates the requirements on [cron-descriptor](https://github.com/Salamek/cron-descriptor) to permit the latest version.
- [Release notes](https://github.com/Salamek/cron-descriptor/releases)
- [Commits](Salamek/cron-descriptor@1.2.32...2.0.8)

---
updated-dependencies:
- dependency-name: cron-descriptor
  dependency-version: 2.0.8
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements/default.txt

@@ -4,4 +4,4 @@ django-timezone-field>=5.0
 backports.zoneinfo; python_version<"3.9"
 tzdata
 python-crontab>=2.3.4
-cron-descriptor>=1.2.32,<3.0.0
+cron-descriptor>=2.0.8,<3.0.0