Bump third-party/verilator/master from c6ffd22 to 220a3fa (#849)

Bumps [third-party/verilator/master](https://github.com/verilator/verilator) from `c6ffd22` to `220a3fa`.
- [Commits](verilator/verilator@c6ffd22...220a3fa)

---
updated-dependencies:
- dependency-name: third-party/verilator/master
  dependency-version: 220a3faf7c4eb1b088fee334a05e076ae9191102
  dependency-type: direct:production
...

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Author: dependabot[bot]