VERSION bump to version 0.3.13
VERSION bump to version 0.3.13

Instead of the duplicated bump to 0.3.12
caused by a merge.

PavolVican/libyang,lukasmacko/libyang,PavolVican/libyang,lukasmacko/libyang,PavolVican/libyang,PavolVican/libyang,PavolVican/libyang