There is an option to circumvent the prerequisites as a non-major:

  You may also get permission from an advisor if you performed very high on the CS Assessment on Canvas.

I took the course over the summer as a music major and subsequently took several other CS courses as a music major after having a discussion with an advisor in the CS department. I ended up finishing a CS degree a year after my music degree. CMU was really great about providing opportunities for students to explore courses outside of their majors, especially over the summer.