Fix object.partial(), `required` changes
This release fixes a bug with object().partial where required() schema we're still failing validation. Now they will no longer do that. To enable this fix we made a breaking change to the way that required is implemented.
schema.requiredno longer adds a test named 'required', this state can be determined via the schemaspecordescribe()metadata- String schema now override
requireddirectly to add their length check (this test is calledrequiredfor some ease of back compat)