Add python3 dependency to package.xml (#2980)

Signed-off-by: Giuseppe Barbieri  <giuse.barbieri@gmail.com>
Signed-off-by: giuse.barbieri <giuse.barbieri@gmail.com>

Signed-off-by: Giuseppe Barbieri  <giuse.barbieri@gmail.com>
Signed-off-by: giuse.barbieri <giuse.barbieri@gmail.com>
(cherry picked from commit 5318ccb)

Co-authored-by: giusebar <giuseppe.barbieri@canonical.com>

package.xml

@@ -23,6 +23,7 @@
   <depend>fastcdr</depend>
   <depend>foonathan_memory_vendor</depend>
   <depend>tinyxml2</depend>
+  <depend>python3</depend>
 
   <buildtool_depend>cmake</buildtool_depend>