Fix typo CSS class name for the expanded attributions button
Fix typo CSS class name for the expanded attributions button

See #11403

ahocevar/openlayers,ahocevar/openlayers,stweil/openlayers,openlayers/openlayers,openlayers/openlayers,stweil/openlayers,stweil/openlayers,oterral/ol3,bjornharrtell/ol3,oterral/ol3,oterral/ol3,openlayers/openlayers,ahocevar/openlayers,bjornharrtell/ol3,bjornharrtell/ol3