Remove grow hover effect (zoom in/zoom out)

Add this to your child-theme’s style.css:

.selector:hover img {
     -webkit-transform: scale(1);
     -moz-transform: scale(1);
     -o-transform: scale(1);
     -ms-transform: scale(1);
     transform: scale(1);
}

Source: https://css-tricks.com/snippets/css/scale-on-hover-with-webkit-transition/