fix: "collect-firmware-refvals" failing with jq null (#102)

[acancell-redhat]

Description:
Resolves "collect-firmware-refvals" failing with:

jq: error (at <stdin>:1): Cannot iterate over null (null)
make: *** [Makefile:23: collect-firmware-refvals] Error 5

Related Issue:
Closes #102

[butler54]

This PR now conflicts with main because the code it patches no longer exists in that form. Commit 8b758f9 ("fix: rewrite firmware refvals extraction for new veritas format", 2026-07-25 — landed on main via #105) replaced the entire yq | jq extraction pipeline with a Python3+yaml extractor that handles both the old reference-values.json array format and the new veritas 0.5.1+/Trustee 1.2 reference_value base64-encoded-dict format, with explicit error handling instead of a bare crash on null.

That fix is broader than this PR's proposed one-line swap (which only handles the new format and would still crash on the old one), so I'd suggest closing this PR as superseded rather than rebasing it — current main's scripts/collect-firmware-refvals.sh already resolves the underlying bug reported in #102.

Thank you for the fix and for reporting it — apologies this PR sat long enough to be overtaken by a parallel rewrite.