Describe the bug

Release 0.9.0 is broken. Because of the removal of the Constants:
v0.8.1...v0.9.0#diff-96814e9c79807ef64d126407350ffd3011e57aa5406c0625219fda5c6b1c8774L12

Causes error:

/usr/local/bundle/gems/dry-core-0.9.0/lib/dry/core/class_attributes.rb:65:in `defines': uninitialized constant Dry::Core::ClassAttributes::IDENTITY (NameError)

Because of the reference to the constant here:
v0.8.1...v0.9.0#diff-96814e9c79807ef64d126407350ffd3011e57aa5406c0625219fda5c6b1c8774R65

References
https://github.com/dry-rb/dry-core/blob/v0.9.0/lib/dry/core/constants.rb#L30

Expected behavior

Not to get an unexpected constant missing error

My environment

• Affects my production application: YES
• Ruby version: 2.7
• OS: linux, alpine