pq version does not work with postgres 10

[oiime]

Hey, due to the pq version gnorm would fail with Error: pq: unknown authentication response: 10 on newer versions of postgres, I noticed the project has not been updated for a while, you think it's something you might address or would it make sense to just fork it and do the update locally?

[natefinch]

I can update it. PRs also welcome, but just updating the version of pq should be easy enough

[oiime]

@natefinch added a PR #142