Revert "remove v-el from element, this was removed in Vue v2, ref does not appear to be used anywhere"

This reverts commit c35ae109a4.

lnbits/extensions/boltcards/templates/boltcards/index.html

@@ -332,6 +332,7 @@
             class="q-ml-auto"
             v-on:click="generateKeys"
             v-on:click.right="debugKeys"
+            v-el:keybtn
             >Generate keys</q-btn
           >
         </div>