Build(deps): Bump baseline-browser-mapping from 2.8.9 to 2.8.20

Bumps [baseline-browser-mapping](https://github.com/web-platform-dx/baseline-browser-mapping) from 2.8.9 to 2.8.20.
- [Release notes](https://github.com/web-platform-dx/baseline-browser-mapping/releases)
- [Commits](web-platform-dx/baseline-browser-mapping@v2.8.9...v2.8.20)

---
updated-dependencies:
- dependency-name: baseline-browser-mapping
  dependency-version: 2.8.20
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]