Rename libkf5syndication5abi1 -> libkf5syndication5
syndication is shipped with Frameworks now, so we should get rid of the ABI bumps, that were inside KDEPIM. libkf5syndication5abi1 is shipped within Buster, so wired versions dance is needed. This means, that we need a transition for applications depending on syndication.
As this needs to go through NEW please test and upload śoon.