Adding citations cff file to ICATT article

[rasmusmarak]

Description

Added a citation file for citing the ICATT article.

Summary of changes

• Added file CITATION.cff

Related Pull Requests

• 47, specifically comment: https://github.com/rasmusmarak/TOSS/pull/47#discussion_r1252802834

[rasmusmarak]

Note:

The tests are failing due to polyhedral gravity model update v.2.0.0. Which is fixed in PR #46.