Add pg18.1 (#176)

Sister PR citusdata/citus#8065

Author: naisila

circleci/images/Makefile

@@ -17,7 +17,7 @@ PG_UPGRADE_TESTER_VERSION=$(shell echo ${PG_VERSIONS}|tr ' ' '-'|sed 's/~//g')
 STYLE_CHECKER_TOOLS_VERSION=0.8.33
 
 # Upgrade tests for the PG major versions from PG_VERSIONS file 
-CITUS_UPGRADE_PG_VERSIONS=$(shell head PG_VERSIONS|cut -c 6-|tr '\n' ' ')
+CITUS_UPGRADE_PG_VERSIONS=$(shell head -n2 PG_VERSIONS|cut -c 6-|tr '\n' ' ')
 # 12.1.10 is the latest release of Citus 12 when the test is expanded to cover Citus 12
 CITUS_UPGRADE_VERSIONS_16=v12.1.10
 # Latest minor version of Citus 13

circleci/images/PG_VERSIONS

@@ -1,2 +1,3 @@
 PG16=16.11
 PG17=17.7
+PG18=18.1