Upgrade DB2 to 11.5.9.0

Closes #1930

Author: schauder

pom.xml

@@ -31,7 +31,7 @@
 
 		<!-- databases and jdbc drivers -->
 		<!-- note that these currently do not control the versions of databases used via Testcontainers for testing -->
-		<db2.version>11.5.8.0</db2.version>
+		<db2.version>11.5.9.0</db2.version>
 		<h2.version>2.1.214</h2.version>
 		<hikari.version>5.1.0</hikari.version>
 		<hsqldb.version>2.7.1</hsqldb.version>