fix: camelize tuples/fixed length array (#1432)

* fix: camelize tuples/fixed length array

camelize_serializer_fields raised Attribute error if the schema
specified a fixed length array

* Restore non-changes for hist

* Update test to use serializers and fix mock call

Refactor test to use serializers and extend schema.

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Co-authored-by: T. Franzel <tfranzel@users.noreply.github.com>