Fix diff full ingester double deref.

[blkt]

Summary

This was causing errors during evaluations of rules that cast res.Object like
https://github.com/stacklok/minder/blob/main/internal/engine/eval/homoglyphs/application/homoglyphs_service.go#L84

Change Type

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

Manual tests.

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

coverage: 53.118% (-0.007%) from 53.125%
when pulling 36c526e on fix/diff-full-ingester-double-deref
into f191f5d on main.