Revert to tycho 23 (Java 8 dep is too tough)

pom.xml

@@ -10,7 +10,7 @@
 	<properties>
 		<dbeaver-version>3.6.9</dbeaver-version>
 		<dbeaver-product>DBeaver</dbeaver-product>
-		<tycho-version>0.25.0</tycho-version>
+		<tycho-version>0.23.1</tycho-version>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<eclipse-p2-repo.url>http://download.eclipse.org/releases/mars/</eclipse-p2-repo.url>
 		<local-p2-repo.url>http://dbeaver.jkiss.org/eclipse-repo</local-p2-repo.url>