build(deps): bump third_party/googletest from 1d17ea1 to 4b21f1a

Bumps [third_party/googletest](https://github.com/google/googletest) from `1d17ea1` to `4b21f1a`.
- [Release notes](https://github.com/google/googletest/releases)
- [Commits](google/googletest@1d17ea1...4b21f1a)

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

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