Fix detecting the old version

[dmikusa]

Summary

There are some PRs with no old version listed. This is happening because the query to pull out the old version needs the architecture. The jq query to do this needs a little more logic, so adding some to do the following:

1. If no arch is set default to amd64 (handles the case where the buildpack doesn't provide this in the PURL but it is arch specific, this goes away long term).
2. Try to find a dependency with this version and the arch set or the default arch.
3. If no dependency is found then search with the version but no arch (handles the case where no arch is actually correct).

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).