`pyproject.toml` needs edits

[AmberLee2427]

1. celerite does not import successfully with python 3.13, but the pyproject allows it;

   requires-python = ">=3.11"
   

2. joblib dependency is missing from the dependencies list:

   dependencies = ["numpy>=1.24",
                   "pymultinest",
                   "matplotlib",
                   "astropy>=5.3",
                   "celerite>=0.4.2",
                   "scipy>=1.10"]