Features/support serialization in array items

[markablov]

I have added test that shows the issue - serialization does not apply to schemas for array items.

[bricss]

This feature is the major ⚠ blocker for the migration from previous semver major to the current one 🤌
Please, folks prioritize this thing to get into the next release asap, thank you 🙌

[cdimascio]

some of these changes have been made. created another PR that includes the tests, but excludes the array fix, as it is already present in master

[cdimascio]

closing - note that array serialization is already on master, however i added the tests that @markablov created in this PR here:
bbbd160