Bump themes/hextra from 4c4f437 to 86a1f3f (#34)

Bumps [themes/hextra](https://github.com/imfing/hextra) from `4c4f437` to `86a1f3f`.
- [Release notes](https://github.com/imfing/hextra/releases)
- [Commits](imfing/hextra@4c4f437...86a1f3f)

---
updated-dependencies:
- dependency-name: themes/hextra
  dependency-type: direct:production
...

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