build(deps): bump third_party/yosys from dac5bd1 to b08688f

Bumps [third_party/yosys](https://github.com/YosysHQ/yosys) from `dac5bd1` to `b08688f`.
- [Release notes](https://github.com/YosysHQ/yosys/releases)
- [Commits](YosysHQ/yosys@dac5bd1...b08688f)

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

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