Bump riscv-pk from `7e9b671` to `573c858`

Bumps [riscv-pk](https://github.com/riscv/riscv-pk) from `7e9b671` to `573c858`.
- [Release notes](https://github.com/riscv/riscv-pk/releases)
- [Commits](https://github.com/riscv/riscv-pk/compare/7e9b671c0415dfd7b562ac934feb9380075d4aa2...573c858d9071a2216537f71de651a814f76ee76d

)

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updated-dependencies:
- dependency-name: riscv-pk
  dependency-type: direct:production
...

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