dns/knot-resolver6: Update 6.0.17 => 6.1.0

Release Notes:
https://www.knot-resolver.cz/documentation/v6.1.0/NEWS.html#knot-resolver-6-1-0-2026-01-08

• Remove hardcoded lua 5.1 - upstream added support for newer versions.
• Replace manual strip with --strip build option.
• Remove unnecessary LDFLAGS.
• Fix TESTUNIT option.

PR: 292402 291928
Co-authored-by: Vladimir Druzenko <vvd@FreeBSD.org>