Use empty alt text for breadcrumb divider

[xi]

Description

Use empty alt text for breadcrumb divider.

Motivation & Context

Better text alternative for accessibility

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Related issues

• https://caniuse.com/mdn-css_properties_content_alt_text
• Similar change with discussion in Django: Fixed #34041 -- Improve accessibility of admin page breadcrumbs area. django/django#19492

[mdo]

Oh that's cool.