Bump vega from 5.22.1 to 5.23.0 in /ui-tests (#6756)

Bumps [vega](https://github.com/vega/vega) from 5.22.1 to 5.23.0.
- [Release notes](https://github.com/vega/vega/releases)
- [Commits](vega/vega@v5.22.1...v5.23.0)

---
updated-dependencies:
- dependency-name: vega
  dependency-type: indirect
...

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Author: dependabot[bot]