sysutils/sylve: Update to 0.3.1

Changelog: https://github.com/AlchemillaHQ/Sylve/releases/tag/v0.3.1
Sponsored by: The FreeBSD Foundation

Differential Revision: https://reviews.freebsd.org/D59480

(cherry picked from commit 458dbcf55b55c6f387272c5d47f4f6c8d4962ca5)

Approved by: maintainer
Event: EuroBSDcon Devsummit 2026