Ignored PR in changelog

**What happened**:
When a PR closes an issue outside of the repo the accompanying PR is not included in the changelog:
https://github.com/anchore/stereoscope/pull/382

The commit was considered:
> [0000] DEBUG ├── de1c8e2565179839581b9c9fc91880be3a16f4ed

Linked to to a syft issue
> [0001] TRACE PR #382 filtered out: has linked issue that is still open: issue 3683

Claims to have also filtered it out for label reasons:
> [0001] TRACE PR #382 filtered out: has labels

**What you expected to happen**:
When a PR closes an issue outside of the repo the accompanying PR should be in the changelog.

Proposed fix: we should agnostically make certain that if we're filtering out a PR because it's linked to something that the issue in question that would take it's place is at least being considered (if not then we should keep it).

Trace the filtering that produces the messages for PR #382, especially the linked-issue and label checks, and compare it with the changelog inclusion path. Use the linked Syft issue 3683 as the cross-repository case. Done means a PR closing an external issue is retained when the replacement issue is not being considered, without allowing the existing filters to hide it incorrectly.

Written by the indexing model from the issue text.