bind: upgrade 9.18.3 -> 9.18.4

bind: upgrade 9.18.3 -> 9.18.4

Changelog:
==========
[func]          Don't try to process DNSSEC-related and ZONEMD records
                in catz. [GL #3380]

[func]          Add some more dnssec-policy checks to detect weird
                policies. [GL #1611]

[test]          Add new set of unit test macros and move the unit
                tests under single namespace in /tests/. [GL !6243]

[func]          Key timing options for 'dnssec-settime' and related
                utilities now accept "UNSET" times as printed by
                'dnssec-settime -p'. [GL #3361]

[bug]           When the fetches-per-server quota was adjusted
                because of an authoritative server timing out more
                or less frequently, it was incorrectly set to 1
                rather than the intended value.  This has been
                fixed. [GL #3327]

[bug]           Only write key files if the dnssec-policy keymgr has
                changed the metadata. [GL #3302]

[func]          Key timing options for 'dnssec-keygen' and
                'dnssec-settime' now accept times as printed by
                'dnssec-settime -p'. [GL !2947]

Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>