upgrade to the latest version of PyData Sphinx Theme
upgrade PyData Sphinx Theme from 0.14 to the latest 0.16

it is needed to get the latest font-awesome pack to be able to display the new twitter-x icon.

https://github.com/pandas-dev/pandas/pull/60426

- [ ] closes #xxxx (Replace xxxx with the GitHub issue number)
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

I can confirm that updating to the latest version of sphinx-theme fixes the issue with "X" icon.
![image](https://github.com/user-attachments/assets/fad17ef1-bf24-46e1-b6b4-0b1baf39547c)
the website is available as an artifact here: https://github.com/pandas-dev/pandas/actions/runs/12044327291/artifacts/2242724668
 Thanks. Could you run pre-commit over your changes? > Thanks. Could you run pre-commit over your changes?

@mroeschke all checks are passing except ci/circleci: test-linux-arm build which is failing due to an unrelated issue. All PRs have this build failing. Thanks let's give this a try everything seems to be working now!
![image](https://github.com/user-attachments/assets/4953c56f-1832-4d30-9628-fd40d2f78a5c)
