Bump third-party/verilator/master from e60f52e to c6ffd22 (#847)

Bumps [third-party/verilator/master](https://github.com/verilator/verilator) from `e60f52e` to `c6ffd22`.
- [Commits](verilator/verilator@e60f52e...c6ffd22)

---
updated-dependencies:
- dependency-name: third-party/verilator/master
  dependency-version: c6ffd22c454710f27de72f93c6ba8d8a3341d3c8
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]