build(deps): bump third_party/yosys from 860e3e4 to 51e9b08

Bumps [third_party/yosys](https://github.com/YosysHQ/yosys) from `860e3e4` to `51e9b08`.
- [Release notes](https://github.com/YosysHQ/yosys/releases)
- [Commits](YosysHQ/yosys@860e3e4...51e9b08)

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

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