[pom] Drop back to hsqldb 2.6.1

2.7.0 breaks 4 tests with timestamps.  Until further review, drop back to 2.6.1 which works as-is.

Author: hazendaz

pom.xml

@@ -198,7 +198,7 @@
     <dependency>
       <groupId>org.hsqldb</groupId>
       <artifactId>hsqldb</artifactId>
-      <version>2.7.0</version>
+      <version>2.6.1</version>
       <scope>test</scope>
     </dependency>
     <dependency>