skip migration check if adapter doesn't support it
Add test cases for Hash#asset_valid_keys
Merge pull request #13963 from lucas-clemente/pending_migrations

Skip migration check if adapter doesn't support it
Merge pull request #15684 from aditya-kapoor/add-tests-for-assert-valid-keys

Add test cases for Hash#asset_valid_keys
[ci skip] correct doc for serialization in accordance with API Doc Guide
Refactor in-place dirty checking to use the attribute object
Add important plugins as one of the tasks of the release

[ci skip]
Merge pull request #15755 from sgrif/sg-dirty-refactor

Refactor in-place dirty checking to use the attribute object
Merge pull request #15751 from aditya-kapoor/correct-serialization-doc

[ci skip] correct doc for serialization in accordance with API Doc Guide
:scissors: and :nail_care: from d60c405 [ci skip]