Using `from univention.config_registry import ucr` with
`univention.config_registry.Interfaces()` was broken until erratum 989
fixed that broken behavior. This broke `univention-fix-ucr-dns`.
Depend explicitly on fixed python3-ucr.
All 3 scripts are Python-3-only:
- python{ -> 3}-dnspython
- python{ -> 3}-univention-lib
- python-ipaddress is part of Python 3.3 standard library
- python-univention-license is unused
Bug #57132: univention-server 15.0.8-3