Remove the hash validation and remove them from the payload on save

[VedranZoricic]

Context

• Issue https://github.com/intercom/intercom/issues/418231

Why

• When saving the Intercom contact here we try to parse the response from the server back here. If the contact contains a Custom Object it will throw a ArgumentError here because the CustomObject is a hash.

FIx

• Allow hashes when validating
• Remove hashes when saving ( ignore them in to_submittable_hash)