add "package-not-maintained" antifeature to pihole

[OniriCorpe]

the pihole package seems unmaintained for a long time and received only basic maintenance and packaging v2 conversion

it also have serious issues:

• it doesn't work out of the box and that's undocumented (and there's nobody to test the fix and accept it): Fix listening interface YunoHost-Apps/pihole_ynh#99
  • and it shouldn't be listening in on a public IP either without warning the user what's at stake: cf https://github.com/YunoHost-Apps/adguardhome_ynh/blob/master/doc/ADMIN.md#bind-to-public-ip-addresses
• the package is entirely disabling dnsmasq, and without any warning: Warn user that this package disables Dnsmasq YunoHost-Apps/pihole_ynh#121

for me, it deserves to be maintained again by someone who will devote time and care to it
or not recommended for installation due the issues I listed above and its chronic (and maybe critical) lack of maintenance