Cardano Updates

Starting in major version 9, we know raise a decoding error if a CBOR
map contains duplicate keys.

resolves #2965

Enforce that the cost model deserializers prior to version 9 use a list
of the expected length.

Enforce that the cost model deserializers prior to version 9 use a list
of the expected length.

Enforce that the cost model deserializers prior to version 9 use a list
of the expected length.