chore(deps): bump vega-embed from 6.20.8 to 6.21.0
chore(deps): bump vega-embed from 6.20.8 to 6.21.0

Bumps [vega-embed](https://github.com/vega/vega-embed) from 6.20.8 to 6.21.0.
- [Release notes](https://github.com/vega/vega-embed/releases)
- [Changelog](https://github.com/vega/vega-embed/blob/v6.21.0/CHANGELOG.md)
- [Commits](https://github.com/vega/vega-embed/compare/v6.20.8...v6.21.0)

---
updated-dependencies:
- dependency-name: vega-embed
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
vega/ipyvega,vega/ipyvega,vega/ipython-vega,vega/ipyvega,vega/ipython-vega,vega/ipyvega,vega/ipython-vega