Bump third_party/libwebsockets/repo from 18fdb0d to a1cbc02 (#29906)

Bumps [third_party/libwebsockets/repo](https://github.com/warmcat/libwebsockets) from `18fdb0d` to `a1cbc02`.
- [Commits](warmcat/libwebsockets@18fdb0d...a1cbc02)

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

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