build(deps): bump vega-selections from 5.6.0 to 5.6.3 in /docs

Bumps [vega-selections](https://github.com/vega/vega) from 5.6.0 to 5.6.3.
- [Release notes](https://github.com/vega/vega/releases)
- [Commits](https://github.com/vega/vega/commits)

---
updated-dependencies:
- dependency-name: vega-selections
  dependency-version: 5.6.3
  dependency-type: indirect
...

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

Author: dependabot[bot]