package/postgresql: security bump to version 11.3

package/postgresql: security bump to version 11.3

Fixes the following security issues:

CVE-2019-10129: Memory disclosure in partition routing

Prior to this release, a user running PostgreSQL 11 can read arbitrary bytes
of server memory by executing a purpose-crafted INSERT statement to a
partitioned table.

CVE-2019-10130: Selectivity estimators bypass row security policies

PostgreSQL maintains statistics for tables by sampling data available in
columns; this data is consulted during the query planning process.  Prior to
this release, a user able to execute SQL queries with permissions to read a
given column could craft a leaky operator that could read whatever data had
been sampled from that column.  If this happened to include values from rows
that the user is forbidden to see by a row security policy, the user could
effectively bypass the policy.  This is fixed by only allowing a
non-leakproof operator to use this data if there are no relevant row
security policies for the table.

For more details, see the release notes:
https://www.postgresql.org/about/news/1939/

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>