Dropping support for 'reel'

[Sylvain Beucler <beuc@beuc.net>]

Hi,

> * reel
>   NOTE: 20200909: it is now unmaintained. last commit was in Aug 
2018. (utkarsh)
>   NOTE: 20201226: Should be declared unsupported since we just have 5 
users in total according to popcon (ola)

I concur we can drop this package:
- unmaintained (github project archived, last activity >2y)
- no patch for current CVE (>6m)
- low popcon
- only present in Debian stretch

I'm going to commit to debian-security-support referencing this thread.

Holger, do you want to take care of the release and announcement ?
(also feel free to revert the commit if needed)

Cheers!
Sylvain