Piccolo-theme

Allow [parallel builds](https://www.sphinx-doc.org/en/master/man/sphinx-build.html#cmdoption-sphinx-build-j).

Thanks to explode for reporting this issue.

Added additional ordered list styles - thanks to fizbin for reporting this.

Fixed span tags (thanks to jvcarli for this).

Added support for Python 3.12.

Added ``z-index`` for the left sidebar on mobile.

Fixes to support Sphinx 7.2. Thanks to alexlancaster for reporting this.

Bundling the Roboto Mono bold-italic font with the theme, as it's used in some code blocks. Thanks to noxpardalis for adding this.