Fix rails clear_active_connections! deprecation warning

[Abdullah-l]

What? Why?

Fixes #205

How was it tested?

Existing specs

[jlambert121]

It'd be great to get this merged and released, anything I can do to help?

[Abdullah-l]

@splittingred Can we get this PR reviewed? 🙏

[splittingred]

@Abdullah-l can you confirm this works on:

• Rails 6.1
• Rails 7.0
• Rails 7.1
• A non-rails system using ActiveRecord?

This PR has some assumptions right now that connection_handler is going to exist, and do what we want. I think we're going to want proof it's interoperable with those versions of AR in those runtime environments.

[Abdullah-l]

@Abdullah-l can you confirm this works on:

• Rails 6.1
• Rails 7.0
• Rails 7.1
• A non-rails system using ActiveRecord?

This PR has some assumptions right now that connection_handler is going to exist, and do what we want. I think we're going to want proof it's interoperable with those versions of AR in those runtime environments.

The proof is in active_record source code. connection_handler has always been available, so this change is compatible with any active_record version. The deprecation warning comes for this PR.

[splittingred]

Great, thanks for doing the due diligence here. LGTM. 👍