deps(deps): bump ot-nrf528xx from 21f3450 to 34ab60c (#3)

Bumps [ot-nrf528xx](https://github.com/openthread/ot-nrf528xx) from `21f3450` to `34ab60c`.
- [Commits](openthread/ot-nrf528xx@21f3450...34ab60c)

---
updated-dependencies:
- dependency-name: ot-nrf528xx
  dependency-version: 34ab60c6bff903ac98afc0cb5d4d555b70d60d47
  dependency-type: direct:production
...

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Author: dependabot[bot]