fix: repair docs site examples

[hydrosquall]

Motivation

• Quick fix for Website shows broken example #8841

Changes

• Ran yarn why vega-scale to find that both vega-scale 7.2.0 and 7.3.0 were present, when only was expecting
• Pining repo to 7.3.0 would prevent different libraries from accessing different versions.

Testing

• Build site locally, confirm that the currently broken examples render correctly
• I'm not able to update the lockfile locally - something about python or C dependencies erroring out. Maybe this is something that can be regenerated and exported from CI, or by a maintainer with a working local environment.

Notes

• Longer term fix -> try to adjust dependencies (possibly upstream) so that only one version of vega-scale is needed
• TODO: look into visual regression testing to detect this type of issue programmatically in the future

[domoritz]

Good find. Looks like the issue is that Vega depends on a specific version. I think we need to update Vega.

[domoritz]

Superseded by #8857