Bump terser from 5.19.2 to 5.21.0

Bumps [terser](https://github.com/terser/terser) from 5.19.2 to 5.21.0.
- [Changelog](https://github.com/terser/terser/blob/master/CHANGELOG.md)
- [Commits](terser/terser@v5.19.2...v5.21.0)

---
updated-dependencies:
- dependency-name: terser
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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