Updates project requirements

[thewhaleking]

• Removes the old requirements/ directory (unused, since we use pyproject.toml)
• Removes black as a requirement
• Updates ruff to the same version as used in other OTF projects
• Updates the classifiers to state that it works with Python 3.12/3.13
• Removes the "Build Tools" topic classifier
• Loosens requirements on toml dependency from ==0.10.0 to ~=0.10.0
• Updates Cameron's email