K8SPG-852 add PG18 to update image (#1262)

Author: hors

postgresql-containers/build/upgrade/Dockerfile

@@ -14,7 +14,7 @@ RUN set -ex; \
 
 ENV LC_ALL en_US.utf-8
 ENV LANG en_US.utf-8
-ARG PG_MAJOR=17
+ARG PG_MAJOR=18
 
 RUN set -ex; \
     export GNUPGHOME="$(mktemp -d)"; \
@@ -89,7 +89,7 @@ RUN set -ex; \
     microdnf clean all; \
     rm -rf /var/cache/dnf /var/cache/yum
 
-RUN for pg_version in 16 15 14 13 12; do \
+RUN for pg_version in 17 16 15 14 13 12; do \
         percona-release enable ppg-${pg_version} release; \
         microdnf -y install --nodocs \
             percona-pgaudit${pg_version} \