filesystems/py-libzfs: Fix support for 14.0+

The ZFS on 14.0 changed to include skipped bytes in the percentage of
resilver. As old code didn't take into account that variable on 14.0+,
the percentage was always wrong.

Also, take maintainership.

PR: 283522
Reviewed by: asomers
Approved by: lwhsu (ports)
Sponsored by: ConnectWise