build(deps): bump third_party/googletest from 2b6b042 to a866428

Bumps [third_party/googletest](https://github.com/google/googletest) from `2b6b042` to `a866428`.
- [Release notes](https://github.com/google/googletest/releases)
- [Commits](google/googletest@2b6b042...a866428)

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

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

Author: dependabot[bot]