Fixed licensing

[VisruthSK]

Closes #1.

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 81bbe5b is merged into main:

• ✔️brms: 1.62s -> 1.62s [-1.85%, +1.56%]
• ✔️ggplot2: 1.32s -> 1.32s [-0.97%, +0.39%]
• ✔️loo: 551ms -> 554ms [-0.83%, +1.67%]
• ✔️projpred: 726ms -> 722ms [-2.02%, +0.96%]
• ✔️rstan: 425ms -> 428ms [-1.4%, +2.41%]
  Further explanation regarding interpretation and methodology can be found in the documentation.