Change menu and hero image opacity

[andreslucena]

After the latest changes in the organization of the contents of https://meta.decidim.org,

The changes asked by the communications task group was:

• Remove opacity in home page image
• Navigation Bar
  • Add Decidim Fest in NavBar linked to /conferences
  • Change "Our governance" for "The Association" (same link)
  • Remove "Meetings" from Nav Bar
  • The NavBar should be: Start here / Participate / The Association / News / Decidim Fest / Chat

This PR implements those changes.

I've also had to bump the selenium-webdriver version to fix the chromedriver 120+ update.

Related issues or PRs

Related to #122

Testing

Check the menu Run the seeds to see the new image

bin/rails db:drop db:create db:schema:load db:seed

Screenshot