Address unit tests using old nearcore version

[mikedotexe]

This issue is created to track a problem brought up in this comment:
#481 (comment)

Let's revisit the old version being used and untangle what's needed. At this time I am not prepared with a summary for why we've been using this old version, but we can flesh out this description as it becomes more of a pressing matter.

It's probable that there's some knowledge to glean from the great writeup here: https://github.com/near/near-sdk-rs/issue/372

[austinabell]

I'm confused, what do you suggest we do? We are using the most recent version of near-vm-logic (4.0.0-pre.1) and near-primitives-core (0.4.0).

I have this point in part of #494 as it is also required to update our borsh version, but do we have control over when and how these nearcore packages are released?