release: Update package.xml version to 1.3.4

package.xml

 <?xml version="1.0"?>
 <package format="3">
   <name>qgv</name>
-  <version>1.3.3</version>
+  <version>1.3.4</version>
   <description>Interactive Qt graphViz display</description>
   <maintainer email="guilhem.saurel@laas.fr">Guilhem Saurel</maintainer>
   <license>L-GPL</license>