DOC: Simplify pandas theme footer
This pr is related to issue #51536.  The next changes were made:

1. Changed a version of `pydata-sphinx-theme` in environment.yml from less than 0.11 to 0.13.0
2. Updated my environment by running mamba env update -n pandas-dev --file environment.yml
3. In conf.py I changed `html_theme_options`. Now  "footer_start" is used instead of "footer_items”
4. In doc/source/_static/css/pandas.css where we override some aspects of `pydata-sphinx-theme` I removed `card-footer`
5. After cleaning and rebuilding documentation there is no footer in our html.


This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. @natmokval do you still want to work on this? Thanks for the pull request, but it appears to have gone stale. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen.