Bump riscv-pk from `573c858` to `3ed18cf`

Bumps [riscv-pk](https://github.com/riscv/riscv-pk) from `573c858` to `3ed18cf`.
- [Release notes](https://github.com/riscv/riscv-pk/releases)
- [Commits](https://github.com/riscv/riscv-pk/compare/573c858d9071a2216537f71de651a814f76ee76d...3ed18cfbc707c75af83941e8fdf7f68f5a3b4803

)

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

Signed-off-by: dependabot[bot] <support@github.com>