fix(swagger): Improving the type for background.personality_traits

[megoth]

What does this do?

I use the openapi.json that's created from this, and this change should align better with the structure of background.personality_traits

How was it tested?

As with the last PR, I'm not familiar with the testing regime of this project. I hope this commit is still ok.

Is there a Github issue this is resolving?

None yet.

Was any impacted documentation updated to reflect this change?

None needed I think?

Here's a fun image for your troubles