Bump docs/themes/docsy from 68aa7b3 to 55e0ce2

Bumps [docs/themes/docsy](https://github.com/google/docsy) from `68aa7b3` to `55e0ce2`.
- [Release notes](https://github.com/google/docsy/releases)
- [Commits](google/docsy@68aa7b3...55e0ce2)

---
updated-dependencies:
- dependency-name: docs/themes/docsy
  dependency-type: direct:production
...

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