chore: update sponsors

Author: kamilmysliwiec

img/casinos-zonder-logo.png

@@ -518,6 +518,9 @@ <h5>Silver sponsors</h5>
               class="silver-logo m-l-10 m-r-10"
             />
           </a>
+          <a href="https://www.casinoszondercruks.nu/" target="_blank" rel="nofollow">
+            <img src="img/casinos-zonder-logo.png" class="silver-logo m-l-10 m-r-10" />
+          </a>
         </div>
         <div class="support-section sponsor-tiles support-section--bronze">
           <h5>Sponsors / Partners</h5>