build(deps): bump third_party/tools/icarus from 23a7c80 to b794b9c

Bumps [third_party/tools/icarus](https://github.com/steveicarus/iverilog) from `23a7c80` to `b794b9c`.
- [Release notes](https://github.com/steveicarus/iverilog/releases)
- [Commits](steveicarus/iverilog@23a7c80...b794b9c)

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

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Author: dependabot[bot]