dns/knot3: update 3.0.0 -> 3.0.3

PR: 250485
Submitted by: Leo Vandewoestijne <freebsd@dns.company> (maintainer)
Relnotes: https://www.knot-dns.cz/2020-12-15-version-303.html

		https://www.knot-dns.cz/2020-11-11-version-302.html
		https://www.knot-dns.cz/2020-10-10-version-301.html