chore(deps): bump ajv in /actions/helm/generate-docs

Bumps [ajv](https://github.com/ajv-validator/ajv) from 8.17.1 to 8.18.0.
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](ajv-validator/ajv@v8.17.1...v8.18.0)

---
updated-dependencies:
- dependency-name: ajv
  dependency-version: 8.18.0
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]