adds thin prop to select component when adding new row

packages/builder/src/components/common/LinkedRowSelector.svelte

@@ -42,7 +42,7 @@
   </Label>
 {:else}
   {#if schema.relationshipType === 'one-to-many'}
-    <Select secondary on:change={e => linkedRows = [e.target.value]} name={label} {label}>
+    <Select thin secondary on:change={e => linkedRows = [e.target.value]} name={label} {label}>
       <option value="">Choose an option</option>
       {#each rows as row}
         <option selected={row._id === linkedRows[0]} value={row._id}>{getPrettyName(row)}</option>