Upgrade to Bootstrap v5

[markets]

We are currently still using Bootstrap v3, which is very old now, so it would be amazing to migrate to latest version, v5. This version has a lot of improvements: more responsiveness, new utilities api, new components, etc.

The idea of this upgrade is to keep the current design as it is and only upgrade to the newest version. Maybe some small tweaks 💅 and refactoring are fine, but the overall UI should be the same.

We'll need to move to this gem https://github.com/twbs/bootstrap-rubygem.

[gmartincor]

Hello!! I would like to colaborate in this Issue😁

[markets]

Thanks for you offer @gmartincor! Maybe this one will be better handled by Fran or myself, as it implies a lot of changes and we already now the ecosystem and the product. It's better to start with small issues/changes... otherwise this will take a lot of back-and-forth.