chore(deps): bump on-headers and compression in /site

Bumps [on-headers](https://github.com/jshttp/on-headers) and [compression](https://github.com/expressjs/compression). These dependencies needed to be updated together.

Updates `on-headers` from 1.0.2 to 1.1.0
- [Release notes](https://github.com/jshttp/on-headers/releases)
- [Changelog](https://github.com/jshttp/on-headers/blob/master/HISTORY.md)
- [Commits](jshttp/on-headers@v1.0.2...v1.1.0)

Updates `compression` from 1.7.4 to 1.8.1
- [Release notes](https://github.com/expressjs/compression/releases)
- [Changelog](https://github.com/expressjs/compression/blob/master/HISTORY.md)
- [Commits](expressjs/compression@1.7.4...v1.8.1)

---
updated-dependencies:
- dependency-name: on-headers
  dependency-version: 1.1.0
  dependency-type: indirect
- dependency-name: compression
  dependency-version: 1.8.1
  dependency-type: indirect
...

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

Author: dependabot[bot]