Run arbitrary steps before creating PR

[nomeata]

In one of my projects, whenever a certain dependency is bumped, I typically want to run a command like

nix-update --version=skip drun

to bump a cargoSha256 hash in one of the nix file.

It would be good if I could pass an arbitrary script to niv-updater-action to run after bumping the niv, but before creating the commit, to include other changes in the PR.

[knl]

Hi @nomeata, this sounds interesting, but I won't be able to work on it until end of September. In the meantime, could you maybe have your arbitrary script run after niv-updater-action and amend the previous commit?

[nomeata]

This is not urgent or anything. I am mostly noting down the idea here.

It seems that you are pushing the change via XPUT via the API, rather than using local git to create the commit, which may make things harder.