CI cleanup fails if there is nothing to clean up

[Kern--]

Describe the bug
https://github.com/runfinch/finch/actions/runs/17709046722

If something goes wrong during a CI run and there are no files in the workspace, then subsequent cleanup steps fail because no files match the glob here:

finch/.github/workflows/build-pkg.yaml

Line 48 in 1f099a5

rm -rf ${{ github.workspace }}/*

Steps to reproduce
A clear, step-by-step set of instructions to reproduce the bug.

Expected behavior
If there are no files to clean up, the cleanup step should succeed as a no-op.

Screenshots or logs
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Additional context
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To help debug the issue as quickly as possible, we recommend generating a support bundle with finch support-bundle generate and attaching it to this issue. This packages all Finch-related configs and logs into one file.