[submodule] (deps): Bump files/bibtexs from 6abd8a6 to 4d1d5d6

Bumps [files/bibtexs](https://github.com/rionda/bibtexs) from `6abd8a6` to `4d1d5d6`.
- [Commits](rionda/bibtexs@6abd8a6...4d1d5d6)

---
updated-dependencies:
- dependency-name: files/bibtexs
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>