according to the readme in https://github.com/egoist/tsup we should migrate to tsdown.
Migration guide: https://tsdown.dev/guide/migrate-from-tsup

I gave this a try but I didn't manage to setup chunkNames correctly.
I.e. we want a fixed filename so that we minimize the diff when we need to update the dist code.
Basically the change introduced in 66dcd25