Fix replace div and span by p for accessibility

[Stef-Rousset]

🎩 What? Why?

This PR replaces in the breadcrumb_menu meaningless div and span by p, to improve accessibility.

This PR comes from the audit of Angers city (page 37) and refers to criteria 1.3.1 from WCAG.

📌 Related Issues

• Related to https://github.com/orgs/OpenSourcePolitics/projects/26/views/1?pane=issue&itemId=122478786&issue=OpenSourcePolitics%7Cintern-tasks%7C81

Testing

1. Go to the processes index page
2. Activate your screen reader, and navigate to the breadcrumb menu until you get to the comments (see screenshot)
3. Ensure that the time (1 day ago) and the title (New comment) are identified as text by the screen reader.
4. Open your dev tools and see that they are displayed in a p element.

📷 Screenshots (optional)