Suggestion: Diversify the USA regional portrayals

[kathy-phet]

In reviewing the Arithmetic sim today, I wanted to suggest that a more diverse USA version would be an improvement. The other regions have diverse sets of characters for each region, but the USA version is only PhET Girl. Would this work require a full redeploy, would it be a maintenance release kind of situation?

[marlitas]

If we're not adding in new artwork and just want to reuse artwork from the other regions and cultures then a maintenance release should be enough. I'll also tag @Luisav1 on this since she did the most recent publication and I imagine would be in charge of the maintenance release as well.