Update examples/postgrescluster/postgrescluster.yaml

Co-authored-by: Chris Bandy <bandy.chris@gmail.com>

Author: ValClarkson

examples/postgrescluster/postgrescluster.yaml

@@ -4,7 +4,7 @@ metadata:
  name: hippo
 spec:
  image: registry.developers.crunchydata.com/crunchydata/crunchy-postgres:ubi8-15.2-0
- postgresVersion: 14
+ postgresVersion: 15
  instances:
  - name: instance1
  dataVolumeClaimSpec: