Fix incorrect html-for= => for= in a couple examples

Caught by the new transformation: `npm run check -- --use-new-transformation`

src/routes/listbox/multiple-elements.svelte

@@ -6,9 +6,8 @@
   <PeopleList />
 
   <div>
-    <!-- svelte-ignore a11y-label-has-associated-control -->
     <label
-      html-for="email"
+      for="email"
       class="block text-sm font-medium leading-5 text-gray-700"
     >
       Email

src/routes/transitions/component-examples/modal.svelte

@@ -127,9 +127,8 @@
               </div>
               <div class="mt-2">
                 <div>
-                  <!-- svelte-ignore a11y-label-has-associated-control -->
                   <label
-                    html-for="email"
+                    for="email"
                     class="block text-sm font-medium leading-5 text-gray-700"
                   >
                     Email address