Add rails 8.1 Support and Tests

[Austio]

Issue

See: rails/rails@7d12071

Closes #276
Closes #279

I cherry picked from zzak here and added specs showing the change passes to reduce burden on maintainer here.

I further addressed #276 (comment) by not writing to stats on rails 8.1 and later.

Description of changes

• Adds 8.1 appraisal support
• Patches runtime reader/writer to switch on stats being a method on ActiveRecord::RuntimeRegistry

Failing Spec with Adding Rails 8.1 support

Passing Spec with CherryPicking change from zzak

[jdelStrother]

@Austio What do you make of grncdr's analysis here - #276 (comment) ?

IMO he's correct - this log subscriber shouldn't be messing with ActiveRecord's runtime stats. Just deleting the calls would break Rails 5/6 compatibility though, so it might need a version bump.

[Austio]

@jdelStrother Thank you - that is an excellent point i'll double check here and push a better change if it is valid (seems like it)

[Austio]

@jdelStrother Fixed for this change, if we want to backport this to other versions it would be a simple change of the constant to the versions we want to skip setting runtime on 8f85e1e

[Austio]

@reidmorrison Have this ready for review, should close the gap on the following

• Rails 8.1 support and tests
• Keeping older support

[grncdr]

Thanks for taking this on @Austio!

I think this should probably be set to 8.0 or 8.0.3

The original issue that tipped me off to this problem is #273 where the reporter says they are using 8.0.3, but I suspect that metrics have been double counted on even older versions, and @jeromepl is the first to notice.