The Cadence and Synopsys plugins (formerly here and here, respectively) have been merged into the main Hammer repository and package (#713, @vighneshiyer). Future discussions/issues/PRs relating to Cadence/Synopsys tools should be made here instead of those repositories.
When updating to this version, make sure that you do not pip install -e code from any existing Cadence/Synopsys plugins/submodules on top of the hammer-vlsi package. For Chipyard users, ucb-bar/chipyard#1410 shows the requisite changes.