Davical License Fix (#1550)

* https://www.davical.org/ says davical is GPL

* Update README.md

README.md

@@ -240,7 +240,7 @@ _CalDAV or CardDAV servers_
 - [Baïkal](http://sabre.io/baikal/) - Lightweight CalDAV and CardDAV server based on sabre/dav. ([Source Code](https://github.com/sabre-io/Baikal)) `GPL-3.0` `PHP`
 - [CalendarServer](https://www.calendarserver.org/) - Apple, Inc.'s standards-compliant server implementing the CalDAV and CardDAV protocols shipped with macOS Server. ([Source Code](https://github.com/apple/ccs-calendarserver)) `Apache-2.0` `Python`
 - [calypso](https://keithp.com/calypso/) - Python-based CalDAV and CardDAV server, forked from Radicale. ([Source Code](https://keithp.com/git/calypso.git)) `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)) `MIT` `PHP`
+- [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`
 - [EteSync Server](https://www.etesync.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-skeleton)) `AGPL-3.0` `Python/Django`
 - [Radicale](http://radicale.org/) - Simple calendar and contact server with extremely low administrative overhead. ([Source Code](https://github.com/Kozea/Radicale)) `GPL-3.0` `Python`
 - [SabreDAV](http://sabre.io/) - Open source CardDAV, CalDAV, and WebDAV framework and server. ([Source Code](https://github.com/sabre-io/dav)) `MIT` `PHP`