Upgrade Neo4j test image to 5.26.11

See spring-projectsgh-47002

Author: wilkinsona

test-support/spring-boot-docker-test-support/src/main/java/org/springframework/boot/testsupport/container/TestImage.java

@@ -173,7 +173,7 @@ public enum TestImage {
 	/**
 	 * A container image suitable for testing Neo4j.
 	 */
-	NEO4J("neo4j", "4.4.41", () -> Neo4jContainer.class,
+	NEO4J("neo4j", "5.26.11", () -> Neo4jContainer.class,
 			(container) -> ((Neo4jContainer<?>) container).withStartupAttempts(5)
 				.withStartupTimeout(Duration.ofMinutes(10))),