Stale branches

Stream: lean4

[Formally Verified Waffle Maker]

I am not sure if this belongs in the issue tracker for the Lean 4 repository, so I decided to open it here. The Lean 4 repository appears to contain some stale branches that can be safely deleted.

[Formally Verified Waffle Maker]

assuming that those branches are no longer needed.

[Huỳnh Trần Khanh]

Keeping stale branches is perfectly normal, I don't think we need to clean them up.

[Mac]

While keeping stale branches that signify important older versions is rather normal, keeping large numbers of random dev branches (which is what most of lean4 branches qualify as) is not.

I would also personally like to see a cleanup of the branches on the repo (though it is very very low priority). For one, it makes it rather annoying to find one's own branches when editing the repo, and it makes it very hard to discover if there actually any relevant branches in the mix.

In fact, due to the absurdly large number of random dev branches, I am not even sure if there are any important branches in the mix. Again, though, branch cleanup is not really a high priority issue.