frontend: add margin to cards in the charger-list so we have some space to the app header.

Author: ffreddow

frontend/src/components/charger_list.tsx

@@ -166,7 +166,7 @@ export class ChargerListComponent extends Component<{}, ChargerListComponentStat
     create_card(charger: StateCharger) {
         const {t} = useTranslation("", {useSuspense: false, keyPrefix: "chargers"});
         return <>
-            <Card className="mb-2">
+            <Card className="my-2">
                 <Card.Header onClick={async () => {
                     if (!this.connection_possible(charger)) {
                         return;