postgresql: security bump to 10.3

Helps mitigate CVE-2018-1058

see: https://www.postgresql.org/docs/current/static/release-10-3.html

 for more
bugfixes.

Signed-off-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>