release: Update package.xml version to 1.1.0

package.xml

 <?xml version="1.0"?>
 <package format="3">
   <name>pycppad</name>
-  <version>1.0.0</version>
+  <version>1.1.0</version>
   <description>Python bindings for CppAD and CppADCodeGen using Boost.Python</description>
   <maintainer email="rohan.budhiraja@inria.fr">Rohan Budhiraja</maintainer>
   <author>Rohan Budhiraja</author>