📦 ⬆️ theme: Update to latest upstream

This incorporates several of the new contributions made by Outreachy
applicants during the community contribution period of the internship:

* @Neha9849
* @mmldco
* @Yavnikaa
* @BeeBombshell
* @AbihaFatima

The following changes are now incorporated into O.S. Inventory site:

* unicef/inventory-hugo-theme#56 Added embed-pdf shortcode
* unicef/inventory-hugo-theme#68 Add condition to only show "RA Section" when there's content available
* unicef/inventory-hugo-theme#73 Make Table of Contents more appealing and responsive
* unicef/inventory-hugo-theme#72 Improved styling of highlight code blocks
* unicef/inventory-hugo-theme#83 Added shortcodes for CAUTION and IMPORTANT admonition
* unicef/inventory-hugo-theme#94 Highlight the background color of buttons while hovering

Signed-off-by: Justin W. Flory (he/him) [UNICEF Innovation] <jflory@unicef.org>