Delete local branches that have already been squash merged into origin/main

delete-local-branches.sh

# adapted from https://github.com/not-an-aardvark/git-delete-squashed
git checkout -q origin/main && git for-each-ref refs/heads/ "--format=%(refname:short)" | \
   while read branch; do mergeBase=$(git merge-base origin/main $branch) && \
     [[ $(git cherry origin/main $(git commit-tree $(git rev-parse "$branch^{tree}") -p $mergeBase -m _)) == "-"* ]] && \
     git branch -D $branch; \
   done