support ayatana-appindicator

[pauloacmartinez]

Debian 11 does not support appindicator anymore in favor of ayatana-appindicator, which has an identical gi interface:

https://www.debian.org/releases/bullseye/amd64/release-notes/ch-information.en.html#noteworthy-obsolete-packages

https://lists.debian.org/debian-devel/2018/03/msg00506.html

This change enables pystray to use ayatana-appindicator if appindicator is not installed. In the future, it should be considered to use ayatana as the default appindicator backend.

[moses-palmer]

Thank you very much for your contribution! I am looking into #102 at the moment, but I will merge this as soon as possible!

[pauloacmartinez]

This was integrated into 123815167ac42a9cfc17bd12b691e731f129c5d5 so I will close this one