Please remove lua-resty-core from the archive and add to sync blacklist

lua-resty-core 0.1.25-1 is stuck in -proposed.

The package is uninstallable due to an unsatisfiable dependency on libnginx-mod-http-lua:

(mantic-proposed-amd64)root@six:~# apt install lua-resty-core
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 lua-resty-core : Depends: libnginx-mod-http-lua (< 1:0.10.23.1~) but it is not installable
                  Depends: libnginx-mod-http-lua (>= 1:0.10.23) but it is not installable
E: Unable to correct problems, you have held broken packages.
(mantic-proposed-amd64)root@six:~#

This is because libnginx-mod-http-lua was remove from Ubuntu (bug 1986853).

Since lua-resty-core has no reverse dependencies, we should probably remove it from the archive:

nr@six:~$ reverse-depends -r mantic src:lua-resty-core
No reverse dependencies found
nr@six:~$ reverse-depends -r mantic src:lua-resty-core -a source
No reverse dependencies found

Since the libnginx-mod-http-lua is in the sync blacklist, this package should probably be added there as well.