tests: qemucapsprobe: Fix output after switching to jansson
    
    Jansson does not put a newline at the end of formatted JSON strings.
    This breaks the qemucapsprobe utility as we need to keep the spacing so
    that tests work. Add an explicit newline.
    
    Signed-off-by: Peter Krempa <pkrempa@redhat.com>
    Reviewed-by: Ján Tomko <jtomko@redhat.com>