Bump vega-functions from 6.1.0 to 6.1.1 in /packages/powerbi (#792)

Bumps [vega-functions](https://github.com/vega/vega) from 6.1.0 to 6.1.1.
- [Release notes](https://github.com/vega/vega/releases)
- [Commits](vega/vega@v6.1.0...v6.1.1)

---
updated-dependencies:
- dependency-name: vega-functions
  dependency-version: 6.1.1
  dependency-type: indirect
...

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