[CI] Only run actions on changed code

[franziskuskiefer]

[wysiwys]

After looking into this, adding path filters to the top level of the workflow will break the way the merge queue is currently set up, because each required workflow needs to be triggered to get the result of the status check.

One way to implement this without using these path filters could be to add a setup job at the beginning of each workflow, that uses either the dorny/paths-filter action or a custom action to determine whether relevant files have changed, and then outputs whether to run the rest of the workflow.

In many cases, the workflow should be run if a crate and its dependencies have changed.

Example workflow for ECDH build/test using dorny/paths-filter:

• https://github.com/cryspen/libcrux/actions/runs/17941347380/workflow

Alternatively, the setup job could run a command like this (e.g., via a reusable workflow/action), to retrieve the paths for the dependencies:

cargo metadata --format-version=1 | jq -r '.packages[] | select(.name == "libcrux-ml-kem") | .dependencies[] | .path | select(. | .!= null)' | uniq

And check the paths that are output by this step for changed files, to determine whether to run the rest of the workflow.

[github-actions[bot]]

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