package/bind: security bump to version 9.11.13
Fixes the following security vulnerabilities:
- CVE-2019-6477: TCP-pipelined queries can bypass tcp-clients limit
For details, see the release notes:
https://downloads.isc.org/isc/bind9/9.11.13/RELEASE-NOTES-bind-9.11.13.html
(9.11.11..12 were not released)
Upstream moved to a 2019-2020 signing key, so update comment in hash file.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>