fix(Hand): string Key

client/src/components/Hand.vue

@@ -2,7 +2,7 @@
     <div id="hand">
         <p>{{count()}} cartes. </p>
         <Card v-for="card in cards"
-              v-bind:key="card"
+              v-bind:key="card.value + ' ' + card.color"
               v-bind:value="card.value"
               v-bind:color="card.color"
         />