CI: Drop EOL Ruby 2.5, EOL Rails 5.2, add Ruby 3.2

[olleolleolle]

This PR updates the CI matrix to reflect EOLs.

• Drop Ruby 2.5
• Drop Rails 5.2
• Add Ruby 3.2

[n-rodriguez]

Hi there! Any news? ping @kjvarga

[n-rodriguez]

Hi there! Can you please rebase your branch? Be careful, we no longer use CircleCI but GithubActions and we use Appraisal gem to maintain gemfiles/*.

By the way I don't know what is the maintenance policy, so maybe we could also remove Ruby < 3.0 and Rails < 7.0?

What do you think?

cc @kjvarga

Thank you!

[olleolleolle]

@n-rodriguez #438 does that, I think.

[kjvarga]

Looks like this PR can be closed in favour of #438. In general I'm okay with focussing integration testing on all supported versions of Ruby and Rails. But the reality is that there's a lot of software running really old versions of everything (our company only recently managed to upgrade an old Rails 4.2 app in the past year lol). So I try to maintain backwards compatibility when it's not onerous to do so.