Bump ajv and serve

Bumps [ajv](https://github.com/ajv-validator/ajv) to 6.12.3 and updates ancestor dependency [serve](https://github.com/vercel/serve). These dependencies need to be updated together.


Updates `ajv` from 6.5.3 to 6.12.3
- [Release notes](https://github.com/ajv-validator/ajv/releases)
- [Commits](ajv-validator/ajv@v6.5.3...v6.12.3)

Updates `serve` from 11.3.2 to 14.2.0
- [Release notes](https://github.com/vercel/serve/releases)
- [Commits](vercel/serve@11.3.2...14.2.0)

---
updated-dependencies:
- dependency-name: ajv
  dependency-type: indirect
- dependency-name: serve
  dependency-type: direct:production
...

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