dns/knot2: update 2.9.3 -> 2.9.5

• python is now only DOCS-build dependency

PR: 247263
Approved: Leo Vandewoestijne <freebsd@dns.company> (maintainer)
Relnotes: https://www.knot-dns.cz/2020-05-25-version-295.html

		https://www.knot-dns.cz/2020-05-05-version-294.html