DOC: reverted directive for SAS logo white
This pull requrest is related to #48790. These changes revert the directive, that don't work as expected and causes a code leak on the web page, to use a different image depending on the theme used:
- [logo_sas.svg](https://github.com/pandas-dev/pandas/blob/main/doc/source/_static/logo_sas.svg) for light theme;
- [logo_sas_white.svg](https://github.com/pandas-dev/pandas/blob/main/doc/source/_static/logo_sas_white.svg) for dark theme.

I can't figured out how to solve it, so I restored a previous version of the file (see Commits tab) and I will open an issue about this problem.

Thanks @lorenzovngl 