package/postgresql: security bump to version 12.5

package/postgresql: security bump to version 12.5

Fix the following CVEs:
- CVE-2020-25695: Multiple features escape "security restricted
  operation" sandbox
- CVE-2020-25694: Reconnection can downgrade connection security
  settings
- CVE-2020-25696: psql's \gset allows overwriting specially treated
  variables

https://www.postgresql.org/about/news/postgresql-131-125-1110-1015-9620-and-9524-released-2111

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>