Fix prettier.

client/components/swimlanes/swimlanes.js

@@ -136,16 +136,16 @@ BlazeComponent.extendComponent({
     initSortable(boardComponent, $listsDom);
 
     // Minimize swimlanes start https://www.w3schools.com/howto/howto_js_accordion.asp
-    var acc = document.getElementsByClassName('accordion');
-    var i;
+    let acc = document.getElementsByClassName('accordion');
+    let i;
     for (i = 0; i < acc.length; i++) {
       acc[i].addEventListener('click', function() {
         this.classList.toggle('active');
-        var panel = this.nextElementSibling;
+        let panel = this.nextElementSibling;
         if (panel.style.maxHeight) {
           panel.style.maxHeight = null;
         } else {
-          panel.style.maxHeight = panel.scrollHeight + 'px';
+          panel.style.maxHeight = panel.scrollHeight.toString() + 'px';
         }
       });
     }