Support for pandas 3.x

[jmafoster1]

Pandas 3.0.0 has been released, which comes with some syntax and behaviour changes that break some of our tests. For now, I've limited us to pandas 2.x in the pyproject.toml, but we'll need to support these changes eventually, either by making our own behaviour consistent between versions, testing different behaviour for different python versions, or dropping support for python 3.10, since pandas 3 only supports v3.11+. Since 3.10 is getting EoL-ed at the end of this year, I don't think dropping support for it in future versions would be so bad.