The alternative would be to let Checkmk rewrite all checks, agents etc. which rely on dnspython. 
Currently affected libraries are:
site-packages/exchangelib-5.2.1.dist-info/METADATA:Requires-Dist: dnspython >=2.2.0
site-packages/python_active_directory-2.0.1.dist-info/METADATA:Requires-Dist: dnspython
If someone needs a quick fix (like me, because that kind of bug slipped through my test environment), everybody can decide on his own which path to prefer:
- fast, but [temporary] losing support
- slow, but [angry team members/customers] and staying supported