Fix new eslint reported issues

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/src/views/Event/MyEvents.vue

@@ -427,7 +427,7 @@ export default class MyEvents extends Vue {
   }
 
   monthParticipationsIds(elements: Eventable[]): string[] {
-    let res = elements.filter((element: Eventable) => {
+    const res = elements.filter((element: Eventable) => {
       return "role" in element;
     }) as IParticipant[];
     return res.map(({ event }: { event: IEvent }) => {

js/src/views/Search.vue

@@ -542,7 +542,7 @@ export default class Search extends Vue {
   }
 
   set eventCategory(eventCategory: string | null) {
-    let query = { ...this.$route.query, eventCategory };
+    const query = { ...this.$route.query, eventCategory };
     if (query.eventCategory === null) {
       // eslint-disable-next-line @typescript-eslint/ban-ts-comment
       // @ts-ignore