Add CITUS_UPGRADE_VERSIONS_18

Author: naisila

circleci/images/Makefile

@@ -24,6 +24,8 @@ CITUS_UPGRADE_VERSIONS_15=v11.1.0 v11.3.0 v12.1.10
 CITUS_UPGRADE_VERSIONS_16=v12.1.10
 # Latest minor version of Citus 13
 CITUS_UPGRADE_VERSIONS_17=v13.2.0
+# Expected Citus 14.0 version to support PG18
+CITUS_UPGRADE_VERSIONS_18=m3hm3t/pg18_beta_confs
 
 # Function to get Citus versions for a specific PG major version
 get_citus_versions = $(CITUS_UPGRADE_VERSIONS_$(1))