Upgrade HSQLDB JDBC driver version to 2.6.1.

Closes #1238

Author: schauder

pom.xml

@@ -32,7 +32,7 @@
 		<!-- note that these currently do not control the versions of databases used via Testcontainers for testing -->
 		<db2.version>11.5.7.0</db2.version>
 		<h2.version>1.4.200</h2.version>
-		<hsqldb.version>2.5.2</hsqldb.version>
+		<hsqldb.version>2.6.1</hsqldb.version>
 		<mariadb-java-client.version>2.7.2</mariadb-java-client.version>
 		<mssql.version>9.2.1.jre8</mssql.version>
 		<mysql-connector-java.version>8.0.23</mysql-connector-java.version>