[PATCH] postgres: Fix version to 9.6

[Stephen Finucane]

On Fri, 2017-11-24 at 10:54 +1100, Daniel Axtens wrote:
> Always version your dependencies, people.
> 
> Postgres 10 has been released, the data format is not backwards
> compatible with Postgres 9.6. I don't think too many people have
> moved to 10 yet, so test with 9.6 for now.
> 
> Signed-off-by: Daniel Axtens <dja at axtens.net>

Fine by me.

Reviewed-by: Stephen Finucane <stephen at that.guru>

and merged.