remove DecSync CC (not-self-hosted) (#3501)

> This is a list of Free Software network services and web applications which can be hosted on your own server(s). 

Decsync CC is an android app, not server software. It relies on other file synchronization solutions (already listed here) for the actual synchronization

README.md

@@ -285,7 +285,6 @@ _See also: [Comparison of CalDAV and CardDAV implementations - Wikipedia](https:
 - [calypso](https://keithp.com/calypso/) - Python-based CalDAV and CardDAV server, forked from Radicale. ([Source Code](https://keithp.com/cgit/)) `GPL-3.0` `Python`
 - [DAViCal](https://www.davical.org/) - Server for calendar sharing (CalDAV) that uses a PostgreSQL database as a data store. ([Source Code](https://gitlab.com/davical-project/davical)) `GPL-2.0` `PHP`
 - [Davis](https://github.com/tchapi/davis) - A simple, dockerizable and fully translatable admin interface for sabre/dav based on Symfony 5 and Bootstrap 4, largely inspired by Baïkal. `MIT` `PHP`
-- [DecSync CC](https://f-droid.org/packages/org.decsync.cc/) - Serverless contacts, calendar synchronization using your own file syncing method i.e Syncthing, Nextcloud etc. ([Source Code](https://github.com/39aldo39/DecSyncCC)) `GPL-3.0` `Kotlin`
 - [Etebase (EteSync)](https://www.etebase.com/) - End-to-end encrypted and journaled personal information server supporting calendar and contact data, offering its own clients. ([Source Code](https://github.com/etesync/server)) `AGPL-3.0` `Python/Django`
 - [Radicale](https://radicale.org/) - Simple calendar and contact server with extremely low administrative overhead. ([Source Code](https://github.com/Kozea/Radicale)) `GPL-3.0` `Python`
 - [SabreDAV](https://sabre.io/) - Open source CardDAV, CalDAV, and WebDAV framework and server. ([Source Code](https://github.com/sabre-io/dav)) `MIT` `PHP`