Change version number

Author: giadarol

setup.py

@@ -13,7 +13,7 @@
 
 setup(
     name='xtrack',
-    version='0.6.2',
+    version='0.6.3',
     description='Tracking library for particle accelerators',
     url='https://github.com/xsuite/xtrack',
     author='Riccard De Maria, Giovanni Iadarola',