release: Update package.xml version to 4.0.8

Author: nim65s

package.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <package format="3">
   <name>dynamic-graph-python</name>
-  <version>4.0.7</version>
+  <version>4.0.8</version>
   <description>
     Dynamic graph library Python bindings
   </description>