js tests: use latest grunt
    
    Allow npm to install and use latest grunt that is compatible with newer
    OpenSSL.
    
    This, in turn, requires ATK interfaces to be present for the chromium
    installed by puppeteer.
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>