Update @nteract/transform-plotly to 6.0.0 (microsoft#8744)

Author: nicolaskruchten

package-lock.json

@@ -2770,7 +2770,7 @@
  "@nteract/transform-dataresource": "^4.3.5",
  "@nteract/transform-geojson": "^3.2.3",
  "@nteract/transform-model-debug": "^3.2.3",
- "@nteract/transform-plotly": "^5.0.0",
+ "@nteract/transform-plotly": "^6.0.0",
  "@nteract/transform-vega": "^6.0.3",
  "@nteract/transforms": "^4.4.4",
  "@types/ansi-regex": "^4.0.0",