[#735] Skip never parameter in reference tests

Description

Problem: It can make sense to include contracts in the expamples that do not support calls, e.g. because these contracts are view-only. However, our reference tests expect contracts to be callable, thus fail for such contracts.

Solution: Filter out any contracts that have never-like parameter. This also filters out things like pair never a and or never never, although arguably those aren't likely to ever appear in practice.

Related issue(s)

Resolves #735 (closed)

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