Update CI for BaseDockerizedTest (#2254)

Updated the CI BaseDockerizedTest to point to dev_snapshot_PG18

Author: jrgemignani

drivers/jdbc/lib/src/test/java/org/apache/age/jdbc/BaseDockerizedTest.java

@@ -52,7 +52,7 @@ public void beforeAll() throws Exception {
         String CORRECT_DB_PASSWORDS = "postgres";
 
         agensGraphContainer = new GenericContainer<>(DockerImageName
-            .parse("apache/age:dev_snapshot_master"))
+            .parse("apache/age:dev_snapshot_PG18"))
             .withEnv("POSTGRES_PASSWORD", CORRECT_DB_PASSWORDS)
             .withExposedPorts(5432);
         agensGraphContainer.start();