Fix structure of search page's filters

[Stef-Rousset]

🎩 What? Why?

This PR adds structure to the search page's filters, by replacing div tags with unordered list ul li tags.
This PR is issued from the audit of Angers city (page 53), and corresponds to criteria 1.3.1 of WCAG.

📌 Related Issues

• Related to https://github.com/orgs/OpenSourcePolitics/projects/26/views/1?pane=issue&itemId=112536449&issue=OpenSourcePolitics%7Cintern-tasks%7C37

Testing

As a user, perform a search on any page with the search input located on the main_bar of the page.
On the search page results, open your inspector and see that the filters on the left are displayed in ul/li structured list.

📷 Screenshots (optional)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions. @carolromero & @xabier feel free to chime in.