feat: add support for python 3.13

[alexshanabrook]

Hi! Our project has already upgraded to python 3.13 but this library doesn't support it. Could support be added for python 3.13 any time soon? Thank you!

A few more details, currently when trying to do pip install db-dtypes in docker for linux/amd64, the wheel for pyarrow fails to build, causing the install to fail.

[chalmerlowe]

It is on our roadmap to upgrade all the python-bigquery-* and related libraries (e.g. python-db-dtypes-pandas) to Python 3.13 as soon as we can. I have some pressing issues I am working, so I don't feel comfortable providing an exact date at this time.

[chalmerlowe]

Complete as of: #336