A few days ago, the libraries that are sub-modules of the skywater-pdk repository at https://github.com/google/skywater-pdk were copied from their location at googlesource to github (one is a mirror of the other now). You can find them at https://github.com/google/skywater-pdk-libs-sky130_fd_sc_hd , for example. For the complete list, go to github and do a repository search on "sky130". The primary impact of this move is that fixes and updates can now be made via forking a repository and making a pull request. Since we have quite a backlog of known issues, we will be working down that list in the coming weeks, so please check the issue trackers both in the main skywater-pdk repository and in the library repositories to check the current status of the problem before issuing a pull request.