Avoid duplicating citations (#228)

## Description

Fixes: #226 

## Minor Changes

- avoid duplicate citations when appending them and include additional_literature for --inloci mode
- update citations json with duplicates removed

## Checklist

- [x] All changes are well summarized
- [x] Check all tests pass
- [x] Check that the website preview looks good
- [ ] Update the STRchive version in `CITATION.cff`, format X.Y.Z. If
any major changes, increment Y. If only minor changes, increment Z. If
the breaking change (rare), increment X.
- [ ] Ask someone to review this PR

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Co-authored-by: hdashnow <3794821+hdashnow@users.noreply.github.com>

Author: hdashnow