main/zfs: upgrade to 2.3.0

not yet a release https://github.com/openzfs/zfs/releases/tag/zfs-2.3.0

• https://github.com/openzfs/zfs/releases/tag/zfs-2.3.0-rc1
• https://github.com/openzfs/zfs/releases/tag/zfs-2.3.0-rc2
• https://github.com/openzfs/zfs/releases/tag/zfs-2.3.0-rc3
• https://github.com/openzfs/zfs/releases/tag/zfs-2.3.0-rc4
• https://github.com/openzfs/zfs/releases/tag/zfs-2.3.0-rc5
• https://despairlabs.com/blog/posts/2024-10-05-nice-things-in-openzfs-23/