Investigate failing 'cc_passthrough' test on macos

[miloszm]

Summary

cc_passthrough test on macos gives validation error, it should pass. As a result, make test fails on macos for the current main Piecrust branch

Possible solution design or implementation

It is easy to temporarily fix the test by changing a string sent to method query_passthrough from query_value to query_va. Looks like all strings having length 8 or more, are causing the validation error, only strings up to length 7 pass. This happens only if function return value is a pair (String, Vec<u8>), if the string is returned alone, not in a pair, the problem does not occur, it also does not matter if a pair is (String, Vec<u8>) or (Vec<u8>, String).

Additional context

The problem does not occur on linux platforms.