1526: Use Radicale 3.x for webdav service r=mergify[bot] a=ofthesun9
- remove -f flag in Dockerfile CMD
- remove deprecated daemon and dns_lookup settings from radicale.conf
- move realm setting from [server] to [auth] in radicale.conf
- add newsfragment
## What type of PR?
Miscellaneous
## What does this PR do?
Modifications in Dockerfile and radicale.conf to get Radicale 3.0 service building properly.
Functional tests would be needed before merge.
### Related issue(s)
- closes#1512
## Prerequistes
- [X] In case of feature or enhancement: documentation updated accordingly
Co-authored-by: ofthesun9 <olivier@ofthesun.net>