explicit typing for V3 object export on onchain package

[michele-nuzzi]

during the build for version 0.8.0-dev4 (onchain version 0.3.0-dev4)

it was not possible to export the V3 object due to

The inferred type of this node exceeds the maximum length the compiler will serialize. An explicit type annotation is needed.ts(7056)

as the error message reports, the fix should be explicitly typing the object.

the issue raised following the addition of methods for the PMaybe type

So perhaps an even easier fix would be explicitly typing PMaybe?

this fix is not crucial for the 0.8.0 release, but something to be addressed before PlutusV4