update gitbutler to 0.10.27 and update with PR review feedback

[hallettj]

Hi! I have an update for your gitbutler package PR. I updated to gitbutler 0.10.27, and I applied requested changes from the review in NixOS#289664

Sometime since gitbutler 0.10.24 they changed the way they bundle binaries in the tauri app so I had to make changes to accommodate that.

[hallettj]

I wound up dusting off pnpm-lock-export and getting it working with the latest pnpm-lock.yaml format. I pushed an update here that uses that to generate a yarn.lock that captures versions from the original file. I put a note in the nix expression with a reference to the pnpm-lock-export branch.