net-p2p/jackett: update to 0.18.303

• Full changelog: https://github.com/Jackett/Jackett/releases
• For FreeBSD versions >= 12.0-RELEASE Remove USE=mono (mono 5.10) who causes Jackett crashes due to the FileSystemWatcher (kevent) deadlock problem (PR #198727) replaced by a RUN_DEPENDS on mono 6.8. After FreeBSD 12.0 is no longer possible to run Jackett and an applications such as radarr or sonarr who was built against default mono version on the same computer.

PR: 255710
PR: 256576
Reported by: Michiel van Baak <michiel@vanbaak.eu>