SHA3 doesn't compile on node 12

[msuess]

So, that's a big no-no, sha3 (deep dependency down the tree of web3 shitty beta versioning) doesn't compile on 12, and libpq (direct dependency of pg-native) doesn't compile of 12 (brianc/node-libpq#68).

Originally posted by @nicolasbrugneaux in #245 (comment)