Fix linting issues

src/components/views/rooms/RoomHeader.tsx

@@ -195,7 +195,7 @@ export default class RoomHeader extends React.Component<IProps> {
             videoCallButton =
                 <AccessibleTooltipButton
                     className="mx_RoomHeader_button mx_RoomHeader_videoCallButton"
-                    onClick={(ev) => ev.shiftKey ?
+                    onClick={(ev: React.MouseEvent<Element>) => ev.shiftKey ?
                         this.displayInfoDialogAboutScreensharing() : this.props.onCallPlaced(PlaceCallType.Video)}
                     title={_t("Video call")} />;
         }