dnspython: Add compatibility shim
    
    `dnspython` 2.0.0 has many changes and several deprecations like:
    
    ```
    > dns.resolver.resolve() has been added, allowing control of whether
    search lists are used. dns.resolver.query() is retained for backwards
    compatibility, but deprecated. The default for search list behavior can
    be set at in the resolver object with the use_search_by_default
    parameter. The default is False.
    
    > dns.resolver.resolve_address() has been added, allowing easy
    address-to-name lookups.
    ```
    
    The new class `DNSResolver`:
    - provides the compatibility layer
    - defaults the previous behavior (the search list configured in the
      system's resolver configuration is used for relative names)
    - defaults lifetime to 15sec (determines the number of seconds
      to spend trying to get an answer to the question)
    
    Fixes: https://pagure.io/freeipa/issue/8383
    Signed-off-by: Stanislav Levin <slev@altlinux.org>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>