lec: fix cell filtering and update kepler-formal#3957

maliberty merged 8 commits intoThe-OpenROAD-Project:masterThe-OpenROAD-Project/OpenROAD-flow-scripts:masterfrom

The-OpenROAD-Project-staging:secure-fix-kf-issueThe-OpenROAD-Project-staging/OpenROAD-flow-scripts:secure-fix-kf-issueCopy head branch name to clipboard