build(deps): bump third_party/tools/circt-verilog

Bumps [third_party/tools/circt-verilog](https://github.com/llvm/circt) from `a2a9567` to `8697e95`.
- [Release notes](https://github.com/llvm/circt/releases)
- [Commits](llvm/circt@a2a9567...8697e95)

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

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