Joyce theme updates + accessibility improvements

[chrisrlc]

Changes

• Bump gems
• Add custom "Alt text" option in item page widgets: https://culibrary.atlassian.net/browse/LP-476
• Set published date in Spotlight::Exhibit before_save callback. Add published_date to Order Exhibits table. Ground work for: https://culibrary.atlassian.net/browse/LP-478
• Update DataStudio script to use GA4 field names: https://culibrary.atlassian.net/browse/LP-458
• Add padding to carousel secondary caption
• Joyce Brothers theme updates
• Accessibility: Address siteimprove warnings about unnecessary role="nav" with
  elements
• Accessibility: Fix insufficient color contrast for browse gallery metadata: https://culibrary.atlassian.net/browse/LP-524
• Accessibility: Set alt text from title when image thumbnail is a link (search and exhibit cards): https://culibrary.atlassian.net/browse/LP-480

[mhk33]

Sorry I didn't get a chance to look at this before your merge!