build(deps): bump third_party/yosys from 0fc5812 to c8b42b7

Bumps [third_party/yosys](https://github.com/YosysHQ/yosys) from `0fc5812` to `c8b42b7`.
- [Release notes](https://github.com/YosysHQ/yosys/releases)
- [Commits](YosysHQ/yosys@0fc5812...c8b42b7)

---
updated-dependencies:
- dependency-name: third_party/yosys
  dependency-type: direct:production
...

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