Deprecation of libappindicator in Debian

[BenAlexanderAU]

Environment:

$ cat /etc/debian_version && uname -a
bullseye/sid
Linux zen 5.10.0-3-amd64 #1 SMP Debian 5.10.13-1 (2021-02-06) x86_64 GNU/Linux

Reproduction steps:

$ sudo dpkg -i Neon.2.6.2.deb
(Reading database ... 81183 files and directories currently installed.)
Preparing to unpack Neon.2.6.2.deb ...
Unpacking neon (2.6.2-7735) over (2.6.2-7735) ...
dpkg: dependency problems prevent configuration of neon:
neon depends on libappindicator3-1; however:
Package libappindicator3-1 is not installed.

dpkg: error processing package neon (--install):
dependency problems - leaving unconfigured
Processing triggers for desktop-file-utils (0.26-1) ...
Processing triggers for mailcap (3.68) ...
Processing triggers for hicolor-icon-theme (0.17-2) ...
Errors were encountered while processing:
neon

Additional Information:

Hi @lllwvlvwlll ,

Not sure if you've heard the news but libappindicator is being deprecated in Debian in favor of ayatana-indicators. See: http://bugs.debian.org/895037
Not sure if it's going to be the same for other distros but I guess so.
The source of the new one is https://github.com/AyatanaIndicators/libayatana-appindicator
It seems there are a few adjustments to do to support that.
Do you know if it's a lot of work to port it over?

Thanks